While connecting to a database copied from a different machine, I get error:

COLLATION UNICODE_CI for CHARACTER SET UTF8 is not installed

which does not offer any hint what is actually wrong. After looking at firebird.log, I see:

Wed Apr 13 18:52:20 2022
	loadICU failed

Wed Apr 13 18:52:20 2022
	initUnicodeCollation failed - UnicodeUtil::Utf16Collation::create failed

Given that I surely have ICU installed, this at least suggests that ICU version could be a problem. And yes, the problem disappears after gfix -icu. However, it would be more user-friendly if:

1. The log contains something like "expected ICU version X, encountered Y", or "ICU version X is not found" or something like this, mentioning that a particular version is not found.
2. The same ICU loading error is added as a secondary code to the status vector, so that the user could understand what's wrong without digging into the server log.