Steps to reproduce the issue

1. I updated all 3rd party extensions on dev websites with Joomla 3.7.5
2. I upgraded to Joomla 3.8

Expected result

That things works

Actual result

1. Additional new entries in Component menu which are nonsens (e.g. JEvents with RussiantranslationForJEvents)
2. Joomla Help: do not work anymore - get: 404 URL invalid
3. The Joomla installer/updater do not overwrite existing extensions anymore. It makes copies and in Manager view you see a new entry for each installation process.

System information (as much as possible)

I tested this with Apache and Windows IIS 7.5, PHP 7.0.23 and 7.1.15. Always the same result.

Additional comments

Sorry, I can't see that version 3.8 is stable. Do you will offer an update 3.7.6 which includes the security fixes only?