Can't sync Gradle after upgrading to Android Studio 2.3

Question

This happens every so often, but I can't seem to resolve it this time. Project builds fine from the command line. This is the error:

Error:org.gradle.api.internal.tasks.DefaultTaskInputs$TaskInputUnionFileCollection cannot be cast to org.gradle.api.internal.file.collections.DefaultConfigurableFileCollection

Possible causes for this unexpected error include:

• Gradle's dependency cache may be corrupt (this sometimes occurs after a network connection timeout.) Re-download dependencies and sync project (requires network)
• The state of a Gradle build process (daemon) may be corrupt. Stopping all Gradle daemons may solve this problem. Stop Gradle build processes (requires restart)
• Your project may be using a third-party plugin which is not compatible with the other plugins in the project or the version of Gradle requested by the project.

In the case of corrupt Gradle processes, you can also try closing the IDE and then killing all Java processes.

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None of the proposed solutions worked. I also tried invalidating caches and manually deleting Gradle caches to force redownload of dependencies and wrapper.

EDIT: "Upgrading to the latest build tools and Gradle version" is not a solution because this issue still exists. And the current workaround to that issue is to disable test coverage "temporarily." As that issue was originally reported 6 months ago (and despite it's being triaged as "critical"), the workaround is not only bad, but not temporary.

Answer 1

The problem seems to be solved for me. This is what I did, including my conjecture as to why it worked.

1. I 'upgraded' my project's Android Gradle Build Tools from 2.1.2 to 2.3.0 ('com.android.tools.build:gradle:2.3.0')
2. I upgraded my Gradle wrapper from 2.14 to 3.3
3. I upgraded my buildToolsVersion from 23.0.3 to 25.0.0.

Having done that, Android Studio finally condescended to sync my project. HOWEVER, when I actually attempted to build the project, I ran into this well known bug. I refuse to 'workaround' this bug, because disabling test coverage is a non-starter.

Having confirmed that bug still holds in the latest build tools, I undid my changes and let AS sync my project again. Voilà, it worked.

I speculate that it worked this time because changing the build tools twice forced some filesystem changes that I missed when I simply deleted some directories in my ~/.gradle/caches/ and ~/.gradle/daemon/ directories.

If I sound at all snarky in this, I apologize, but it's incredibly frustrating for the Android Studio team to release a 'stable' version of their IDE that has undocumented, (near?) breaking changes. For them to attempt to force an 'upgrade' to a build tool that has a known critical defect (oh, but it's only testing, and who cares about that?) is just wrong.