I canceled a running Gradle build and now I get the following message whenever I restart it:
Could not create service of type FileHasher using BuildSessionServices.createFileHasher().
> Cannot lock file hash cache (/data/.gradle/6.4.1/fileHashes) as it has already been locked by this process.
The solution is to look for the gradle process and to kill it. In my case I had to look for a running java process.
So in htop I searched for java
and terminated it. That solved my problem.