I dont sure if its a bug because browsers work with different encode/chars.

Already use UTF-8 anyway:

 - Opera 10 - Chrome 

Uses a different encoding but has no problem with req param (so ASCII is still OK):

Firefox 1-4 (UTF-16 lower bytes) Safari 4-5 (ISO-8859-1) IE:Mac 5 (MacRoman) IE 5-8 (CP_ACP) IEMobile 6-8 (CP_ACP) Netscape 4 (CP_ACP) Opera 5 (CP_ACP) 

https://bugzilla.mozilla.org/show_bug.cgi?id=41489#c90

About his doubts. The Basic authentication does not provide support for non-ISO-8859-1 characters.

You can try to convert the characters in .htaccess to UTF8, not tested, not sure if it works. How to change the default encoding to UTF-8 for Apache

I recommend using another authentication method or create a login page.

If other colleagues have a better solution, please let me know.

I dont sure if its a bug because browsers work with different encode/chars.

Already use UTF-8 anyway:

 - Opera 10 - Chrome 

Uses a different encoding but has no problem with req param (so ASCII is still OK):

Firefox 1-4 (UTF-16 lower bytes) Safari 4-5 (ISO-8859-1) IE:Mac 5 (MacRoman) IE 5-8 (CP_ACP) IEMobile 6-8 (CP_ACP) Netscape 4 (CP_ACP) Opera 5 (CP_ACP) 

https://bugzilla.mozilla.org/show_bug.cgi?id=41489#c90

About his doubts. The Basic authentication does not provide support for non-ISO-8859-1 characters.

You can try to convert the characters in .htaccess to UTF8, not tested, not sure if it works. How to change the default encoding to UTF-8 for Apache

I recommend using another authentication method or create a login page.

If other colleagues have a better solution, please let me know.