The Firefox for Android app has always had a complicated build process - we're cramping a complex cross-platform browser engine and all the related components that make it work on Android into one package. In its current form, it lives in the Firefox mono-repo at mozilla-central (now mozilla-firefox using the git repository).
I wanted to document my "artifact-mode" environment here since it's worked quite successfully for me for many years with minor changes.
NOTE: After a fresh clone of the mono-repo, don't forget to first run and follow the prompts of ./mach bootstrap .
mozconfig
My mozconfig below is enabled for artifact mode, but occasionally I switch between various configurations. You can see those commented out, with these few extra notes:
I like to separate out my objdirs to avoid cache pollution between the different build types. I think you can get away without needing to specify this and an objdir for your build type and arch will be generated.
sccache speeds up the native portion of full builds after the first slow one, but it's a hit or miss if you fetch from the remote repository but don't need to rebuild as often.
I don't care to manually run the clobber step, and I don't truly appreciate why that isn't always automatically done.
# Build GeckoView/Firefox for Android:
ac_add_options --enable-application=mobile/android
# Targeting the following architecture.
# For regular phones, no --target is needed.
# For x86 emulators (and x86 devices, which are uncommon):
# ac_add_options --target=i686
# For newer phones or Apple silicon
ac_add_options --target=aarch64
# For x86_64 emulators (and x86_64 devices, which are even less common):
# ac_add_options --target=x86_64
# sccache will significantly speed up your builds by caching
# compilation results. The Firefox build system will download
# sccache automatically.
# This only works for non-artifact builds.
#ac_add_options --with-ccache=sccache
# Enable artifact builds; manager-mode.
ac_add_options --enable-artifact-builds
# Write build artifacts to..
## Full build dir
#mk_add_options MOZ_OBJDIR=./objdir-droid
#mk_add_options MOZ_OBJDIR=./objdir-desktop
## Artifact builds
mk_add_options MOZ_OBJDIR=./objdir-frontend
# Automatic clobbering; don't ask me.
mk_add_options AUTOCLOBBER=1
JAVA_HOME
Sometimes you might find yourself needing to run a (non-mach) command in the terminal. Those typically will need to invoke some parts of gradle for an Android build, so it's best to make sure those are using the same JDK as the bootstrapped one in the mono-repo. This avoids weird build errors where something that compiles in one place isn't working in another (like Android Studio).
The location for the JDKs are typically in ~/.mozbuild/jdk/, and if you've between around for ~6 months you end up with multiple versions after every JDK bump:
$ ls -l ~/.mozbuild/jdk/
drwxr-xr-x@ - jalmeida 15 Apr 2025 jdk-17.0.15+6
drwxr-xr-x@ - jalmeida 15 Jul 2025 jdk-17.0.16+8
drwxr-xr-x@ - jalmeida 21 Oct 2025 jdk-17.0.17+10
drwxr-xr-x@ - jalmeida 20 Jan 09:00 jdk-17.0.18+8
drwxr-xr-x@ - jalmeida 26 Feb 15:04 mozboot
You can find some way to point your latest JDK to one location or you can be lazy like me and pick the latest version to assign as your JAVA_HOME property by adding this to your shell's RC file:
export JAVA_HOME="$(ls -1dr -- $HOME/.mozbuild/jdk/jdk-* | head -n 1)/Contents/Home"
Android Studio
Similarly for Android Studio, let's do the same so that environment is identical. Head to, Settings | Build, Execution, Deployment | Build Tools | Gradle, and ensure that "Gradle JDK" path is set to JAVA_HOME.
Lately, the default seems to be for it to follow GRADLE_LOCAL_JAVA_HOME which is a property we can't easily override, so we have to manually set this ourselves.
Using the same Android SDK also helps speed things up and avoids source confusion. You can typically find it in ~/.mozbuild/android-sdk-macosx and update it at Settings | Languages & Frameworks | Android SDK.
Debugging
This section is for miscellaneous build error situations that come-up, but assuming mach build work and there are no known Android build changes, my solution has typically always been the same.
For example, the other day I fetched another engineers patch to test out locally1 as part of reviewing it where I faced the error message below:
Execution failed for task ':components:feature-pwa:compileDebugKotlin'.
FAILURE: Build failed with an exception.
* What went wrong:
Execution failed for task ':components:feature-pwa:compileDebugKotlin'.
> A failure occurred while executing org.jetbrains.kotlin.compilerRunner.GradleCompilerRunnerWithWorkers$GradleKotlinCompilerWorkAction
> Internal compiler error. See log for more details
* Try:
> Run with --info or --debug option to get more log output.
> Run with --scan to generate a Build Scan (powered by Develocity).
> Get more help at https://help.gradle.org.
* Exception is:
org.gradle.api.tasks.TaskExecutionException: Execution failed for task ':components:feature-pwa:compileDebugKotlin'.
at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.lambda$executeIfValid$1(ExecuteActionsTaskExecuter.java:135)
at org.gradle.internal.Try$Failure.ifSuccessfulOrElse(Try.java:288)
at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeIfValid(ExecuteActionsTaskExecuter.java:133)
at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.execute(ExecuteActionsTaskExecuter.java:121)
at org.gradle.api.internal.tasks.execution.ProblemsTaskPathTrackingTaskExecuter.execute(ProblemsTaskPathTrackingTaskExecuter.java:41)
at org.gradle.api.internal.tasks.execution.FinalizePropertiesTaskExecuter.execute(FinalizePropertiesTaskExecuter.java:46)
at org.gradle.api.internal.tasks.execution.ResolveTaskExecutionModeExecuter.execute(ResolveTaskExecutionModeExecuter.java:51)
at org.gradle.api.internal.tasks.execution.SkipTaskWithNoActionsExecuter.execute(SkipTaskWithNoActionsExecuter.java:57)
at org.gradle.api.internal.tasks.execution.SkipOnlyIfTaskExecuter.execute(SkipOnlyIfTaskExecuter.java:74)
at org.gradle.api.internal.tasks.execution.CatchExceptionTaskExecuter.execute(CatchExceptionTaskExecuter.java:36)
at org.gradle.api.internal.tasks.execution.EventFiringTaskExecuter$1.executeTask(EventFiringTaskExecuter.java:77)
at org.gradle.api.internal.tasks.execution.EventFiringTaskExecuter$1.call(EventFiringTaskExecuter.java:55)
at org.gradle.api.internal.tasks.execution.EventFiringTaskExecuter$1.call(EventFiringTaskExecuter.java:52)
at org.gradle.internal.operations.DefaultBuildOperationRunner$CallableBuildOperationWorker.execute(DefaultBuildOperationRunner.java:209)
at org.gradle.internal.operations.DefaultBuildOperationRunner$CallableBuildOperationWorker.execute(DefaultBuildOperationRunner.java:204)
at org.gradle.internal.operations.DefaultBuildOperationRunner$2.execute(DefaultBuildOperationRunner.java:66)
at org.gradle.internal.operations.DefaultBuildOperationRunner$2.execute(DefaultBuildOperationRunner.java:59)
at org.gradle.internal.operations.DefaultBuildOperationRunner.execute(DefaultBuildOperationRunner.java:166)
at org.gradle.internal.operations.DefaultBuildOperationRunner.execute(DefaultBuildOperationRunner.java:59)
at org.gradle.internal.operations.DefaultBuildOperationRunner.call(DefaultBuildOperationRunner.java:53)
at org.gradle.api.internal.tasks.execution.EventFiringTaskExecuter.execute(EventFiringTaskExecuter.java:52)
at org.gradle.execution.plan.DefaultNodeExecutor.executeLocalTaskNode(DefaultNodeExecutor.java:55)
at org.gradle.execution.plan.DefaultNodeExecutor.execute(DefaultNodeExecutor.java:34)
at org.gradle.execution.taskgraph.DefaultTaskExecutionGraph$InvokeNodeExecutorsAction.execute(DefaultTaskExecutionGraph.java:355)
at org.gradle.execution.taskgraph.DefaultTaskExecutionGraph$InvokeNodeExecutorsAction.execute(DefaultTaskExecutionGraph.java:343)
at org.gradle.execution.taskgraph.DefaultTaskExecutionGraph$BuildOperationAwareExecutionAction.lambda$execute$0(DefaultTaskExecutionGraph.java:339)
at org.gradle.internal.operations.CurrentBuildOperationRef.with(CurrentBuildOperationRef.java:84)
at org.gradle.execution.taskgraph.DefaultTaskExecutionGraph$BuildOperationAwareExecutionAction.execute(DefaultTaskExecutionGraph.java:339)
at org.gradle.execution.taskgraph.DefaultTaskExecutionGraph$BuildOperationAwareExecutionAction.execute(DefaultTaskExecutionGraph.java:328)
at org.gradle.execution.plan.DefaultPlanExecutor$ExecutorWorker.execute(DefaultPlanExecutor.java:459)
at org.gradle.execution.plan.DefaultPlanExecutor$ExecutorWorker.run(DefaultPlanExecutor.java:376)
at org.gradle.internal.concurrent.ExecutorPolicy$CatchAndRecordFailures.onExecute(ExecutorPolicy.java:64)
at org.gradle.internal.concurrent.AbstractManagedExecutor$1.run(AbstractManagedExecutor.java:47)
Caused by: org.gradle.workers.internal.DefaultWorkerExecutor$WorkExecutionException: A failure occurred while executing org.jetbrains.kotlin.compilerRunner.GradleCompilerRunnerWithWorkers$GradleKotlinCompilerWorkAction
at org.gradle.workers.internal.DefaultWorkerExecutor$WorkItemExecution.waitForCompletion(DefaultWorkerExecutor.java:289)
at org.gradle.internal.work.DefaultAsyncWorkTracker.lambda$waitForItemsAndGatherFailures$2(DefaultAsyncWorkTracker.java:130)
at org.gradle.internal.Factories$1.create(Factories.java:33)
at org.gradle.internal.work.DefaultWorkerLeaseService.lambda$withoutLocks$2(DefaultWorkerLeaseService.java:344)
at org.gradle.internal.work.ResourceLockStatistics$1.measure(ResourceLockStatistics.java:42)
at org.gradle.internal.work.DefaultWorkerLeaseService.withoutLocks(DefaultWorkerLeaseService.java:342)
at org.gradle.internal.work.DefaultWorkerLeaseService.withoutLocks(DefaultWorkerLeaseService.java:326)
at org.gradle.internal.work.DefaultWorkerLeaseService.withoutLock(DefaultWorkerLeaseService.java:331)
at org.gradle.internal.work.DefaultAsyncWorkTracker.waitForItemsAndGatherFailures(DefaultAsyncWorkTracker.java:126)
at org.gradle.internal.work.DefaultAsyncWorkTracker.waitForItemsAndGatherFailures(DefaultAsyncWorkTracker.java:92)
at org.gradle.internal.work.DefaultAsyncWorkTracker.waitForAll(DefaultAsyncWorkTracker.java:78)
at org.gradle.internal.work.DefaultAsyncWorkTracker.waitForCompletion(DefaultAsyncWorkTracker.java:66)
at org.gradle.api.internal.tasks.execution.TaskExecution$3.run(TaskExecution.java:260)
at org.gradle.internal.operations.DefaultBuildOperationRunner$1.execute(DefaultBuildOperationRunner.java:29)
at org.gradle.internal.operations.DefaultBuildOperationRunner$1.execute(DefaultBuildOperationRunner.java:26)
at org.gradle.internal.operations.DefaultBuildOperationRunner$2.execute(DefaultBuildOperationRunner.java:66)
at org.gradle.internal.operations.DefaultBuildOperationRunner$2.execute(DefaultBuildOperationRunner.java:59)
at org.gradle.internal.operations.DefaultBuildOperationRunner.execute(DefaultBuildOperationRunner.java:166)
at org.gradle.internal.operations.DefaultBuildOperationRunner.execute(DefaultBuildOperationRunner.java:59)
at org.gradle.internal.operations.DefaultBuildOperationRunner.run(DefaultBuildOperationRunner.java:47)
at org.gradle.api.internal.tasks.execution.TaskExecution.executeAction(TaskExecution.java:237)
at org.gradle.api.internal.tasks.execution.TaskExecution.executeActions(TaskExecution.java:220)
at org.gradle.api.internal.tasks.execution.TaskExecution.executeWithPreviousOutputFiles(TaskExecution.java:203)
at org.gradle.api.internal.tasks.execution.TaskExecution.execute(TaskExecution.java:170)
at org.gradle.internal.execution.steps.ExecuteStep.executeInternal(ExecuteStep.java:105)
at org.gradle.internal.execution.steps.ExecuteStep.access$000(ExecuteStep.java:44)
at org.gradle.internal.execution.steps.ExecuteStep$1.call(ExecuteStep.java:59)
at org.gradle.internal.execution.steps.ExecuteStep$1.call(ExecuteStep.java:56)
at org.gradle.internal.operations.DefaultBuildOperationRunner$CallableBuildOperationWorker.execute(DefaultBuildOperationRunner.java:209)
at org.gradle.internal.operations.DefaultBuildOperationRunner$CallableBuildOperationWorker.execute(DefaultBuildOperationRunner.java:204)
at org.gradle.internal.operations.DefaultBuildOperationRunner$2.execute(DefaultBuildOperationRunner.java:66)
at org.gradle.internal.operations.DefaultBuildOperationRunner$2.execute(DefaultBuildOperationRunner.java:59)
at org.gradle.internal.operations.DefaultBuildOperationRunner.execute(DefaultBuildOperationRunner.java:166)
at org.gradle.internal.operations.DefaultBuildOperationRunner.execute(DefaultBuildOperationRunner.java:59)
at org.gradle.internal.operations.DefaultBuildOperationRunner.call(DefaultBuildOperationRunner.java:53)
at org.gradle.internal.execution.steps.ExecuteStep.execute(ExecuteStep.java:56)
at org.gradle.internal.execution.steps.ExecuteStep.execute(ExecuteStep.java:44)
at org.gradle.internal.execution.steps.CancelExecutionStep.execute(CancelExecutionStep.java:42)
at org.gradle.internal.execution.steps.TimeoutStep.executeWithoutTimeout(TimeoutStep.java:75)
at org.gradle.internal.execution.steps.TimeoutStep.execute(TimeoutStep.java:55)
at org.gradle.internal.execution.steps.PreCreateOutputParentsStep.execute(PreCreateOutputParentsStep.java:50)
at org.gradle.internal.execution.steps.PreCreateOutputParentsStep.execute(PreCreateOutputParentsStep.java:28)
at org.gradle.internal.execution.steps.RemovePreviousOutputsStep.execute(RemovePreviousOutputsStep.java:68)
at org.gradle.internal.execution.steps.RemovePreviousOutputsStep.execute(RemovePreviousOutputsStep.java:38)
at org.gradle.internal.execution.steps.BroadcastChangingOutputsStep.execute(BroadcastChangingOutputsStep.java:61)
at org.gradle.internal.execution.steps.BroadcastChangingOutputsStep.execute(BroadcastChangingOutputsStep.java:26)
at org.gradle.internal.execution.steps.CaptureOutputsAfterExecutionStep.execute(CaptureOutputsAfterExecutionStep.java:69)
at org.gradle.internal.execution.steps.CaptureOutputsAfterExecutionStep.execute(CaptureOutputsAfterExecutionStep.java:46)
at org.gradle.internal.execution.steps.ResolveInputChangesStep.execute(ResolveInputChangesStep.java:39)
at org.gradle.internal.execution.steps.ResolveInputChangesStep.execute(ResolveInputChangesStep.java:28)
at org.gradle.internal.execution.steps.BuildCacheStep.executeWithoutCache(BuildCacheStep.java:189)
at org.gradle.internal.execution.steps.BuildCacheStep.lambda$execute$1(BuildCacheStep.java:75)
at org.gradle.internal.Either$Right.fold(Either.java:176)
at org.gradle.internal.execution.caching.CachingState.fold(CachingState.java:62)
at org.gradle.internal.execution.steps.BuildCacheStep.execute(BuildCacheStep.java:73)
at org.gradle.internal.execution.steps.BuildCacheStep.execute(BuildCacheStep.java:48)
at org.gradle.internal.execution.steps.StoreExecutionStateStep.execute(StoreExecutionStateStep.java:46)
at org.gradle.internal.execution.steps.StoreExecutionStateStep.execute(StoreExecutionStateStep.java:35)
at org.gradle.internal.execution.steps.SkipUpToDateStep.executeBecause(SkipUpToDateStep.java:75)
at org.gradle.internal.execution.steps.SkipUpToDateStep.lambda$execute$2(SkipUpToDateStep.java:53)
at org.gradle.internal.execution.steps.SkipUpToDateStep.execute(SkipUpToDateStep.java:53)
at org.gradle.internal.execution.steps.SkipUpToDateStep.execute(SkipUpToDateStep.java:35)
at org.gradle.internal.execution.steps.legacy.MarkSnapshottingInputsFinishedStep.execute(MarkSnapshottingInputsFinishedStep.java:37)
at org.gradle.internal.execution.steps.legacy.MarkSnapshottingInputsFinishedStep.execute(MarkSnapshottingInputsFinishedStep.java:27)
at org.gradle.internal.execution.steps.ResolveIncrementalCachingStateStep.executeDelegate(ResolveIncrementalCachingStateStep.java:49)
at org.gradle.internal.execution.steps.ResolveIncrementalCachingStateStep.executeDelegate(ResolveIncrementalCachingStateStep.java:27)
at org.gradle.internal.execution.steps.AbstractResolveCachingStateStep.execute(AbstractResolveCachingStateStep.java:71)
at org.gradle.internal.execution.steps.AbstractResolveCachingStateStep.execute(AbstractResolveCachingStateStep.java:39)
at org.gradle.internal.execution.steps.ResolveChangesStep.execute(ResolveChangesStep.java:64)
at org.gradle.internal.execution.steps.ResolveChangesStep.execute(ResolveChangesStep.java:35)
at org.gradle.internal.execution.steps.ValidateStep.execute(ValidateStep.java:62)
at org.gradle.internal.execution.steps.ValidateStep.execute(ValidateStep.java:40)
at org.gradle.internal.execution.steps.AbstractCaptureStateBeforeExecutionStep.execute(AbstractCaptureStateBeforeExecutionStep.java:76)
at org.gradle.internal.execution.steps.AbstractCaptureStateBeforeExecutionStep.execute(AbstractCaptureStateBeforeExecutionStep.java:45)
at org.gradle.internal.execution.steps.AbstractSkipEmptyWorkStep.executeWithNonEmptySources(AbstractSkipEmptyWorkStep.java:136)
at org.gradle.internal.execution.steps.AbstractSkipEmptyWorkStep.execute(AbstractSkipEmptyWorkStep.java:66)
at org.gradle.internal.execution.steps.AbstractSkipEmptyWorkStep.execute(AbstractSkipEmptyWorkStep.java:38)
at org.gradle.internal.execution.steps.legacy.MarkSnapshottingInputsStartedStep.execute(MarkSnapshottingInputsStartedStep.java:38)
at org.gradle.internal.execution.steps.LoadPreviousExecutionStateStep.execute(LoadPreviousExecutionStateStep.java:36)
at org.gradle.internal.execution.steps.LoadPreviousExecutionStateStep.execute(LoadPreviousExecutionStateStep.java:23)
at org.gradle.internal.execution.steps.HandleStaleOutputsStep.execute(HandleStaleOutputsStep.java:75)
at org.gradle.internal.execution.steps.HandleStaleOutputsStep.execute(HandleStaleOutputsStep.java:41)
at org.gradle.internal.execution.steps.AssignMutableWorkspaceStep.lambda$execute$0(AssignMutableWorkspaceStep.java:35)
at org.gradle.api.internal.tasks.execution.TaskExecution$4.withWorkspace(TaskExecution.java:297)
at org.gradle.internal.execution.steps.AssignMutableWorkspaceStep.execute(AssignMutableWorkspaceStep.java:31)
at org.gradle.internal.execution.steps.AssignMutableWorkspaceStep.execute(AssignMutableWorkspaceStep.java:22)
at org.gradle.internal.execution.steps.ChoosePipelineStep.execute(ChoosePipelineStep.java:40)
at org.gradle.internal.execution.steps.ChoosePipelineStep.execute(ChoosePipelineStep.java:23)
at org.gradle.internal.execution.steps.ExecuteWorkBuildOperationFiringStep.lambda$execute$2(ExecuteWorkBuildOperationFiringStep.java:67)
at org.gradle.internal.execution.steps.ExecuteWorkBuildOperationFiringStep.execute(ExecuteWorkBuildOperationFiringStep.java:67)
at org.gradle.internal.execution.steps.ExecuteWorkBuildOperationFiringStep.execute(ExecuteWorkBuildOperationFiringStep.java:39)
at org.gradle.internal.execution.steps.IdentityCacheStep.execute(IdentityCacheStep.java:46)
at org.gradle.internal.execution.steps.IdentityCacheStep.execute(IdentityCacheStep.java:34)
at org.gradle.internal.execution.steps.IdentifyStep.execute(IdentifyStep.java:44)
at org.gradle.internal.execution.steps.IdentifyStep.execute(IdentifyStep.java:31)
at org.gradle.internal.execution.impl.DefaultExecutionEngine$1.execute(DefaultExecutionEngine.java:64)
at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeIfValid(ExecuteActionsTaskExecuter.java:132)
... 30 more
Caused by: org.jetbrains.kotlin.gradle.tasks.FailedCompilationException: Internal compiler error. See log for more details
at org.jetbrains.kotlin.gradle.tasks.TasksUtilsKt.throwExceptionIfCompilationFailed(tasksUtils.kt:22)
at org.jetbrains.kotlin.compilerRunner.GradleKotlinCompilerWork.run(GradleKotlinCompilerWork.kt:112)
at org.jetbrains.kotlin.compilerRunner.GradleCompilerRunnerWithWorkers$GradleKotlinCompilerWorkAction.execute(GradleCompilerRunnerWithWorkers.kt:75)
at org.gradle.workers.internal.DefaultWorkerServer.execute(DefaultWorkerServer.java:68)
at org.gradle.workers.internal.NoIsolationWorkerFactory$1$1.create(NoIsolationWorkerFactory.java:64)
at org.gradle.workers.internal.NoIsolationWorkerFactory$1$1.create(NoIsolationWorkerFactory.java:61)
at org.gradle.internal.classloader.ClassLoaderUtils.executeInClassloader(ClassLoaderUtils.java:100)
at org.gradle.workers.internal.NoIsolationWorkerFactory$1.lambda$execute$0(NoIsolationWorkerFactory.java:61)
at org.gradle.workers.internal.AbstractWorker$1.call(AbstractWorker.java:44)
at org.gradle.workers.internal.AbstractWorker$1.call(AbstractWorker.java:41)
at org.gradle.internal.operations.DefaultBuildOperationRunner$CallableBuildOperationWorker.execute(DefaultBuildOperationRunner.java:209)
at org.gradle.internal.operations.DefaultBuildOperationRunner$CallableBuildOperationWorker.execute(DefaultBuildOperationRunner.java:204)
at org.gradle.internal.operations.DefaultBuildOperationRunner$2.execute(DefaultBuildOperationRunner.java:66)
at org.gradle.internal.operations.DefaultBuildOperationRunner$2.execute(DefaultBuildOperationRunner.java:59)
at org.gradle.internal.operations.DefaultBuildOperationRunner.execute(DefaultBuildOperationRunner.java:166)
at org.gradle.internal.operations.DefaultBuildOperationRunner.execute(DefaultBuildOperationRunner.java:59)
at org.gradle.internal.operations.DefaultBuildOperationRunner.call(DefaultBuildOperationRunner.java:53)
at org.gradle.workers.internal.AbstractWorker.executeWrappedInBuildOperation(AbstractWorker.java:41)
at org.gradle.workers.internal.NoIsolationWorkerFactory$1.execute(NoIsolationWorkerFactory.java:58)
at org.gradle.workers.internal.DefaultWorkerExecutor.lambda$submitWork$0(DefaultWorkerExecutor.java:176)
at org.gradle.internal.work.DefaultConditionalExecutionQueue$ExecutionRunner.runExecution(DefaultConditionalExecutionQueue.java:194)
at org.gradle.internal.work.DefaultConditionalExecutionQueue$ExecutionRunner.access$700(DefaultConditionalExecutionQueue.java:127)
at org.gradle.internal.work.DefaultConditionalExecutionQueue$ExecutionRunner$1.run(DefaultConditionalExecutionQueue.java:169)
at org.gradle.internal.Factories$1.create(Factories.java:33)
at org.gradle.internal.work.DefaultWorkerLeaseService.lambda$withLocksAcquired$0(DefaultWorkerLeaseService.java:269)
at org.gradle.internal.work.ResourceLockStatistics$1.measure(ResourceLockStatistics.java:42)
at org.gradle.internal.work.DefaultWorkerLeaseService.withLocksAcquired(DefaultWorkerLeaseService.java:267)
at org.gradle.internal.work.DefaultWorkerLeaseService.withLocks(DefaultWorkerLeaseService.java:259)
at org.gradle.internal.work.DefaultWorkerLeaseService.runAsWorkerThread(DefaultWorkerLeaseService.java:127)
at org.gradle.internal.work.DefaultWorkerLeaseService.runAsWorkerThread(DefaultWorkerLeaseService.java:132)
at org.gradle.internal.work.DefaultConditionalExecutionQueue$ExecutionRunner.runBatch(DefaultConditionalExecutionQueue.java:164)
at org.gradle.internal.work.DefaultConditionalExecutionQueue$ExecutionRunner.run(DefaultConditionalExecutionQueue.java:133)
... 2 more
The full trace was long and didn't seem related to a code failure in the module itself. So I employed the solution, which is always the same:
./mach build
In Android Studio, File > Sync Project with Gradle Files.
Yup, that's all. Very simple and boring.
1
With Jujutsu, this is the moz-phab command I use which has made it easier to manage review patches: moz-phab patch <patch-id> --no-branch --apply-to main@origin
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Hey everyone, we've been working on some exciting changes, and want to share them with you.
But first, let me introduce myself. I am Christos, the new Sr. Developer Relations engineer in Add-ons, and I'm excited to write my first post on the Add-ons engineering blog.
Deprecations and changes
To start, I'm looking at a couple of features that are going away: avoiding content script execution in extension contexts, decoupling file access from host permissions, and improving the display of pageAction SVG icon.
executeScript / registerContentScript in moz-extension documents
Deprecated: Firefox 149 Removed: Firefox 152
Starting in Firefox Nightly 149 and scheduled for Firefox 152, the scripting and tabs injection APIs no longer inject into moz-extension://documents. This change brings the API in line with broader efforts to discourage string-based code execution in extension contexts, alongside the default CSP that restricts script-src to extension URLs and the removal of remote source allowlisting in MV3 (bug 1581608).
Firefox emits a warning when this restriction is met, so you are aware of and can address any use of this process in your extensions. This is an example of the warning message:
Content Script execution in moz-extension document has been deprecated and it has been blocked
To work around this change, you can:
Import scripts directly in the extension page's HTML.
Use module imports or standard <script> tags in extension documents.
Restructure code to avoid dynamic code execution patterns. An extension can run code in its documents dynamically by registering a runtime.onMessage listener in the document's script, then sending a message to trigger execution of the required code.
File access becomes opt-in
Target: Firefox 152
Extensions requesting file://*/ or <all_urls> currently trigger the "Access your data for all websites" permission message, and when granted, can run content scripts in file:-URLs. From Firefox 152, file access in extensions requires an opt-in for all extensions, including those already installed (bug 2034168).
pageAction SVG icon CSS filter (automatic color scheme)
Removed: Firefox 152
Firefox has been automatically applying a greyscale and brightness CSS filter to pageAction (address bar button) SVG icons when a dark theme is active. This was intended to improve contrast, but it actually reduced contrast for multi-color icons and caused poor visibility for some extensions, such as Firefox Multi-Account Containers.
For icons that adapt to light and dark color schemes, you can now use @media (prefers-color-scheme: dark) in the SVG icon, or the MV3 action manifest key, and specify theme_icons.
Here is an example of how to use a `prefers-color-scheme` media query in a pageAction SVG icon to control how the icon adapts to dark mode:
Use of prefers-color-scheme media queries is also allowed in MV2 browserAction and MV3 action SVG icons as an alternative to the theme_icons manifest properties.
Now to the new stuff. Here, you get the ability to use popups without user activation, initial support for the new tab split view feature, and WebAuthn RP ID assertion.
openPopup without user activation (Firefox Desktop)
Available: Firefox 149 Desktop
action.openPopup() and browserAction.openPopup() no longer require a user gesture on Firefox Desktop. You can open your extension's popup programmatically, e.g., in response to a native-messaging event, an alarm, or a background-script condition.
This change is part of the ongoing cross-browser alignment work in the WebExtensions Community Group to harmonize popup behavior across engines.
Example
Before (Firefox < 149): must hang off a user gesture, e.g., a context menu click:
browser.menus.create({
id: "nudge",
title: "Open popup",
contexts: ["all"],
});
browser.menus.onClicked.addListener((info) => {
if (info.menuItemId === "nudge") {
browser.action.openPopup(); // user clicked the menu → allowed
}
});
After (Firefox ≥ 149) - same intent, no user gesture needed, fires from a timer:
browser.alarms.create("nudge", { delayInMinutes: 1 });
browser.alarms.onAlarm.addListener((alarm) => {
if (alarm.name === "nudge") {
browser.action.openPopup(); // works without a click
}
});
It's the same call with the same result, but only the trigger changes from a user-action handler to any background event.
It's the same call with the same result, but only the trigger changes from a user-action handler to any background event.
splitViewId in the tabs API
Available: Firefox 149
Firefox 149 introduces a new read-onlysplitViewIdproperty on the tabs.Tab object to expose Firefox's new split view feature (where two tabs are displayed side-by-side in one window). Split views are treated as one unit, and Web Extensions treat them the same way.
In Firefox 150, extensions can swap tabs within a split view. This update also resolves a confusing issue where using the user interface to reverse tab order incorrectly reports the tabs.onMoved event with inaccurate values. Additionally, Firefox introduces unsplitting behavior for web extensions: when tabs.move() is called with split-view tabs positioned separately (non-adjacently) in the array. Now, after the call, Firefox removes the split view rather than keeping the tabs locked together.
Here is an example of using the new splitViewId property.
// Log whenever a tab joins or leaves a split view.
browser.tabs.onUpdated.addListener((tabId, changeInfo) => {
if (!("splitViewId" in changeInfo)) return;
if (changeInfo.splitViewId === browser.tabs.SPLIT_VIEW_ID_NONE) {
console.log(`Tab ${tabId} left its split view`);
} else {
console.log(`Tab ${tabId} joined split view ${changeInfo.splitViewId}`);
}
});
// Firefox desktop also supports a filter to limite onUpdated events:
// }, { properties: ["splitViewId"] });
Firefox 151 enables extensions to move split views in tab groups. More improvements are coming, such as the ability to create split views from extensions (bug 2016928).
WebAuthn RP ID assertion
Available: Firefox 150
Previously, web extensions couldn't use WebAuthn credentials registered on their company's website or mobile apps. When extensions tried to set a custom Relying Party ID (RP ID) in navigator.credentials.create() or navigator.credentials.get(), Firefox rejected it with "SecurityError: The operation is insecure."
With Firefox 150, Extensions can now assert aWebAuthn RP IDfor any domain they have host permissions for
when calling navigator.credentials.create() or navigator.credentials.get(). This applies to both the publicKey.rp.id field during credential creation and the publicKey.rpId field during authentication.
A critical detail for server-side validation: When relying party servers validate credentials created by extensions, they must account for different origin formats across browsers. In Chrome, the origin follows the pattern chrome-extension://extensionid, which matches the extension's location.origin. Firefox 150 introduces a new stable origin format: moz-extension://hash, where the hash is a 64-character SHA-256 representation of the extension ID (using characters a-p to represent hex values). Importantly, this hash-based origin is the same all users, unlike Firefox's existing UUID-based moz-extension:// URLs used for extension documents.
To extract the origin from a credential for validation:
let clientData = JSON.parse(new TextDecoder().decode(
publicKeyCredential.response.clientDataJSON
));
console.log(clientData.origin);
It's been a very busy couple of months as we've reworked processes & priorities and established a roadmap for both iOS and Android. We are determining how best we can coordinate with the community, and think that our roadmap for the year has a good balance of fixes and features. Today, I want to talk about our contributors and pull requests, Notifications in the Android app, progress in the iOS app, and an overview of our roadmap for both apps this year.
Contributors & Pull Requests
We are so grateful for the support and code contributions of many members, whether building items on our roadmap, improving the user experience, or, of course, translating. As we work on our roadmap priorities, we will make time to review PRs and will discuss them weekly, and prioritize those that help solve issues and bugs or align with our roadmap items. Please be patient with our Pull Request pipeline. Typically, in working with the community, we try to react very quickly.
Roadmap
For Android, we've chosen the items on our roadmap because we think these will be the highest-impact features and bring the most value to everyone. Our focus this year is to simplify and modernize the Android codebase. This means reworking some of the architecture. This will be super helpful for us to move more quickly and will reduce complex bugs. The app has an older codebase, and like many older ones, it has its challenges. We have three full-time Android engineers and several community contributors, and we hope to better position ourselves to move quickly. At a high level, Android is focusing on the rearchitecture, a better Message List experience, and Message Reader screens. We are also simplifying how users can connect to Thunder Mail as we open it up.
Notifications
One thing that is at the top of my mind right now, too, is Push Notifications, specifically changes that Google has made to background processes, which affect our Notifications. We are looking into what we can do to solve this, so know that it has become a top priority for us. I've been asked, "Why is it so hard for Thunderbird to get Push Notifications right?" and I wanted to speak to some of the challenges we have. Most apps' Notifications are triggered by their own web services, which then send Notifications through Apple or Google, who pass them to users. But email is different. In an email client, we typically don't own our own backend services, but other companies do (Microsoft, Google, Hotmail, Yahoo, Proton, etc.). And they can have their own flavors of SMTP - how we get the emails, and no specific Push Notification implementation.
So we have a work around: polling those providers ever X minutes asking for new emails, and triggering local notifications - but we can't hook into a native Push Notification process like your banking app for example. This is under the IMAP implementation. The JMAP implementation (think modern email protocols) has something in place we can more readily consume. Another challenge is how the battery is affected by how often we poll the providers, and we need specific permissions from Google to run this process in the background. Those permissions changed recently which is why Notifications are having issues.
I've simplified some pieces here, but hopefully that gives you an idea of some of the complexity and tradeoffs that we are working with. With all of that said, this is veryimportant to us, and is our users' biggest pain point. It is becoming our biggest need for a fix. I'll give an update on where that sits within the roadmap next progress report when we have explored what solutions we can provide.
iOS Progress
For the iOS roadmap, everything is moving along well. We have been wrapping up most of our IMAP & SMTP tickets, and we are moving into the Account Data pieces to manage accounts and authorizations. We will also be having a new member join us in the next couple of weeks. This will add some speed, but we've made good progress in getting the inner pieces together - what I consider the most complex parts. As we move to more standard mobile backend pieces and more standard UI, we leave the world of unknown unknowns, and will be picking up steam.
At a high level our iOS roadmap is build out these screens:
Account Setup and Drawer
Messages: List, Reader, Compose, Search
And have these pieces in place:
IMAP
SMTP
MIME
OAuth
Encryption
Email Composition
And our target is still end of the year for the iOS release.
Thank You!
Again we are so grateful to you, our community, for your support, and we are excited for this next quarter as we start to see the fruits of our labors.
