Actually, after disabling one addon after the other, I likely found the culprit:
FRITZ!Box AddOn 2.0.4
It's not easy to find, but the update url embedded in the install.rdf is still pointing to a valid location:
em:updateURL="http://download.avm.de/fritz.box/tools/fritzbox_addon/addon4ff/update.rdf"
You can open a download location here:
Actually I'm re-enabling each disabled addon one by one, I already changed back to german localization and my preferred dark theme.
I attach the addon and its .oprefs to this post for further investigation:
FRITZBoxAddOn{2.0.4}.xpi
- The problematic addon as it seems by now
- (596.48 KiB) Downloaded 590 times
FRITZBoxAddOn{2.0.4}.oprefs.zip
- The .oprefs of it - zipped because of forum restrictions
- (458 Bytes) Downloaded 593 times
Edit:
As it seems ONLY the issue with FEBE is solved by disabling the Fritzbox Addon, but not the FECT issue ...
Edit 2:
Yes, all addons and themes and language settings set back to normal, but without Fritzbox Addon, FEBE works.
FECT shows the following weird behavior:
When I click on 'Continue' inside 'Start a new session', and then on 'Cancel' and then RESTART the browser, I can choose 'Continue with next iteration' ...
After each step done I have to restart the browser to continue...
