$! contains error message in locale's language and encoding as bytes, it isn't decoded into Unicode scalar:

$ LANG=ru_RU.UTF-8 perl -CS -MEncode=decode -E '
  sub show {
    printf "is_utf8=%d, length=%d, msg=%s\n",
      utf8::is_utf8($_), length, $_;
  }
  $_=$!=111;
  show();
  $_=decode("UTF-8", $_);
  show();
'
is_utf8=0, length=40, msg=Ð Ñоединении оÑказано
is_utf8=1, length=21, msg=[here should be correct Russian "connection 
+refused" but perlmonks's parser turn it into html entities]

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So, when we've nice Unicode-enabled application, which correctly write Unicode messages into UTF-8 log files, and then we get some error and try to write $! into log we get junk instead of error message.

It's clear what it's nearly impossible to manually decode('UTF-8') in each and every place we get $! - especially because this error may happens inside 3rd-party module. So, is it possible to somehow fix/workaround this issue without forcing LANG=en_US.UTF-8?

In reply to encoding for $! by powerman

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