Android Studio 3.0.1 Error: Gradle project sync failed. Basic functionality (e.g. editing, debugging) will not work properly

Question

I've installed Android studio 3.0.1 then tried to build very first app by choosing an empty activity, but I've got this message:

Gradle project sync failed. Basic functionality (e.g. editing, debugging) will not work properly

and the error message like this:

Unable to resolve dependency for ':app@releaseUnitTest/compileClasspath': Could not resolve com.android.support:appcompat-v7:26.1.0. Could not resolve com.android.support:appcompat-v7:26.1.0. Required by: project :app Could not resolve com.android.support:appcompat-v7:26.1.0. > Could not parse POM https://dl.google.com/dl/android/maven2/com/android/support/appcompat-v7/26.1.0/appcompat-v7-26.1.0.pom > Already seen doctype.

The first part of log message is like this:

2018-01-03 11:11:12,671 [d thread 8] WARN - ect.sync.idea.ProjectSetUpTask - Already seen doctype. Consult IDE log for more details (Help | Show Log) 2018-01-03 11:11:12,671 [d thread 8] INFO - e.project.sync.GradleSyncState - Gradle sync failed: Already seen doctype.

I've tried some suggested solutions like changing gradle version, update Kotlin plugin(!) and so, but they didn't work.

Any solution?

Answer 1

This problem occurs when the Build Tools Version is not set for the project. You just set the build tools version by following this process...

By opening your project structure [File->Project Structure] and selecting the Build Tools Version from app's property tab in Modules section.

This will add build tools version to your gradle file (Module:app) and re-sync the project.