Gradle build for Android in Unity fails, saying that it could not find intellij-core.jar

Question

So thats what I have tried:

• Building different projects (same thing)
• Reinstalling sdk, jdk, and Unity Editor (newbie gotos)

I have also found very similar problem from today: Android Studio - Could not find intellij-core.jar yet the only gradle.build file that I found was the one generated with Unity in Temp folder that overwrites itself after every build start.

Unity 2018.2.13f1, Windows 10 x64, Fresh Android Studio 3.2.1, jdk1.8.0_192

Here is a console log:
Short

A problem occurred configuring root project 'gradleOut'.
> Could not resolve all files for configuration ':classpath'.
   > Could not find intellij-core.jar (com.android.tools.external.com-intellij:intellij-core:26.0.1).
     Searched in the following locations:
         https://jcenter.bintray.com/com/android/tools/external/com-intellij/intellij-core/26.0.1/intellij-core-26.0.1.jar

Long

CommandInvokationFailure: Gradle build failed. 
C:\Program Files\Java\jdk1.8.0_192\bin\java.exe -classpath "C:\Program Files (x86)\Unity Editors\2018.2.13f1\Editor\Data\PlaybackEngines\AndroidPlayer\Tools\gradle\lib\gradle-launcher-4.2.1.jar" org.gradle.launcher.GradleMain "-Dorg.gradle.jvmargs=-Xmx2048m" "assembleRelease"

stderr[

FAILURE: Build failed with an exception.

* What went wrong:
A problem occurred configuring root project 'gradleOut'.
> Could not resolve all files for configuration ':classpath'.
   > Could not find intellij-core.jar (com.android.tools.external.com-intellij:intellij-core:26.0.1).
     Searched in the following locations:
         https://jcenter.bintray.com/com/android/tools/external/com-intellij/intellij-core/26.0.1/intellij-core-26.0.1.jar

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.

* Get more help at https://help.gradle.org

BUILD FAILED in 1s
]
stdout[

]
exit code: 1
UnityEditor.Android.Command.WaitForProgramToRun (UnityEditor.Utils.Program p, UnityEditor.Android.WaitingForProcessToExit waitingForProcessToExit, System.String errorMsg)
UnityEditor.Android.Command.Run (System.Diagnostics.ProcessStartInfo psi, UnityEditor.Android.WaitingForProcessToExit waitingForProcessToExit, System.String errorMsg)
UnityEditor.Android.AndroidJavaTools.RunJava (System.String args, System.String workingdir, System.Action`1 progress, System.String error)
UnityEditor.Android.GradleWrapper.Run (UnityEditor.Android.AndroidJavaTools javaTools, System.String workingdir, System.String task, System.Action`1 progress)
Rethrow as GradleInvokationException: Gradle build failed
UnityEditor.Android.GradleWrapper.Run (UnityEditor.Android.AndroidJavaTools javaTools, System.String workingdir, System.String task, System.Action`1 progress)
UnityEditor.Android.PostProcessor.Tasks.BuildGradleProject.Execute (UnityEditor.Android.PostProcessor.PostProcessorContext context)
UnityEditor.Android.PostProcessor.PostProcessRunner.RunAllTasks (UnityEditor.Android.PostProcessor.PostProcessorContext context)
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)

Answer 1

Here's the only solution that worked for me since I'm behind a proxy.

1. Go to the .gradle folder (default is under C:\Users\<name>\).
2. Create a file called gradle.properties under this folder.
3. Add the following:

---

#http proxy setup
systemProp.http.proxyHost=<your proxy URL>
systemProp.http.proxyPort=<your proxy Port>
systemProp.http.nonProxyHosts=*.nonproxyrepos.com|localhost

#https proxy setup
systemProp.https.proxyHost=<your proxy URL>
systemProp.https.proxyPort=<your proxy Port>
systemProp.https.nonProxyHosts=*.nonproxyrepos.com|localhost

4. Reopen unity and build !

Answer 2

Here's what worked for me, as reported here:

1. Go into the Player Settings
2. Under Publishing Settings tick the box for Custom Gradle Template (Unity then creates a build.gradle template for you)
3. The template is in Assets > Plugins > Android > mainTemplate.gradle
4. Open that file in something like Notepad

5. Change ONLY THIS:

   repositories { jcenter() google() } to repositories { google() jcenter() }

6. Save the file then try the build again. Not a perfect solution but it should work until Unity/Android fixes the issue. I'm not sure whether this can become undone by upgrading Unity, but I do know that it has to be done per project.