We updated our LMS from moodle 3.7.2 to 3.9+ according to upgrade guide recommendations, then we update all installed language packs via Administration> Site administration> Language> Language packs
And we have 2 problems:
1) the some strings of language customization that we saved in moodle 3.7 were lost
2) When saving strings of language customization, an error occurs: "error / Unable to find the filename for the component block_course_overview" while the "block_course_overview" block has never been set (neither in 3.7 nor in 3.9).
Could you please explain what we have done wrong when updating?
Only clearing (truncate) of the `tool_customlang_components` and `tool_customlang` tables has helped.