Hi @BartSmaga,
Thanks for reporting the issue!
This error seems to be related to the ongoing bintray.com issue, see:
From our status page:
There’s an ongoing, sporadic issue related to Android dependency downloads from bintray.com, manifesting in “Received status code 500 from server: Internal Server Error” errors sometimes.
The issue is reported on the bintray status page, for more information please see: http://status.bintray.com/incidents/gc6bhb1hb6m6
Note: a reliable mitigation can be to configure a Bitrise Build Cache for your Android project, you can find a guide for the setup at: How to cache Gradle dependencies
If you have any questions please let us know!