Thanks for your reply.

I've looked at my code again before posting here full module source and found string in my AUTOLOAD sub that stoped my app:

carp "value now is ".$value;
# ..this message will not be printed if $value is utf8 string
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So I found the real error source: combination carp & use diagnostics

Can you check following code in your environment?:

#!/usr/bin/perl

use strict;
#use diagnostics; # when uncommented will freeze the app
use Carp;

print "before carp\n";
carp "\x{41f}\x{440}\x{438}\x{432}\x{435}\x{442}"; #'Hello' in Russian
print "after carp\n";
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Is this a normal reaction on "use diagnostics"?