When i remove utf8::all; , i get 500 - Internal Server Error message. And nothing in the server (lighttpd) log.

When i tried to run the script from my command line, like

1.pl tekst="фывафыа" i got no error message w/ turned off utf8::all; and

Status: 500
Content-type: text/html

<h1>Software error:</h1>
<pre>Cannot decode string with wide characters at /usr/lib/i386-linux-
+gnu/perl/5.24/Encode.pm line 202.</pre>
<p>For help, please send mail to this site's webmaster, giving this er
+ror message and the time and date of the error.</p>
[Sat Dec 31 16:27:02 2016] 1.pl: Cannot decode string with wide charac
+ters at /usr/lib/i386-linux-gnu/perl/5.24/Encode.pm line 202.
[download]

w/ turned on -- that simply shows that the string is already in UTF-8.

Mine versions of software are: perl 5.24.1, and CGI -- 4.35.