Error: Cannot decode string with wide characters at /usr/lib/x86_64-linux-gnu/perl/5.20/Encode.pm line 215.
~~~~
+> Looks as though you might be able to get a Python-style backtrace for this
+> by setting `$Carp::Verbose = 1`.
+>
+> The error is that we're taking some string (which string? only a backtrace
+> would tell you) that is already flagged as Unicode, and trying to decode
+> it from byte-blob to Unicode again, analogous to this Python:
+>
+> some_bytes.decode('utf-8').decode('utf-8')
+>
+> --[[smcv]]
+> >
+> > I couldn't figure out where to set that Carp thing - it doesn't work simply by setting it in /usr/bin/ikiwiki - so i am not sure how to use this. However, with some debugging code in Encode.pm, i was able to find a case of double-encoding - in the left menu, for example, which is the source of the Encode.pm crash.
+> >
+> > It seems that some unicode semantics changed in Perl 5.20, or more precisely, in Encode.pm 2.53, according to [this](https://code.activestate.com/lists/perl-unicode/3314/). 5.20 does have significant Unicode changes, but I am not sure they are related (see [perldelta](https://metacpan.org/pod/distribution/perl/pod/perldelta.pod)). Doing more archeology, it seems that Encode.pm is indeed where the problem started, all the way back in [commit 8005a82](https://github.com/dankogai/p5-encode/commit/8005a82d8aa83024d72b14e66d9eb97d82029eeb#diff-f3330aa405ffb7e3fec2395c1fc953ac) (august 2013), taken from [pull request #11](https://github.com/dankogai/p5-encode/pull/11) which expressively forbids double-decoding, in effect failing like python does in the above example you gave (Perl used to silently succeed instead, a rather big change if you ask me).
+> >
+> > So stepping back, it seems that this would be a bug in Ikiwiki. It could be in any of those places:
+> >
+> > ~~~~
+> > anarcat@marcos:ikiwiki$ grep -r decode_utf8 IkiWiki* | wc -l
+> > 31
+> > ~~~~
+> >
+> > Now the fun part is to determine which one should be turned off... or should we duplicate the logic that was removed in decode_utf8, or make a safe_decode_utf8 for ourselves? --[[anarcat]]
+
The apache logs yield:
~~~~
http://paste.debian.net/plain/119944
This is a major bug which should probably be fixed before jessie, yet i can't seem to find a severity statement in reportbug that would justify blocking the release based on this - unless we consider non-english speakers as "most" users (i don't know the demographics well enough). It certainly makes ikiwiki completely unusable for my users that operate on the web interface in french... --[[anarcat]]
+
+Note that on this one page, i can't even get the textarea to display and i immediately get `Error: Cannot decode string with wide characters at /usr/lib/x86_64-linux-gnu/perl/5.20/Encode.pm line 215`: http://anarc.at/ikiwiki.cgi?do=edit&page=hardware%2Fserver%2Fmarcos.
+
+Also note that this is the same as [[forum/"Error: cannot decode string with wide characters" on Mageia Linux x86-64 Cauldron]], I believe. The backtrace I get here is:
+
+~~~~
+Error: Cannot decode string with wide characters at /usr/lib/x86_64-linux-gnu/perl/5.20/Encode.pm line 215. Encode::decode_utf8("**Menu**\x{d}\x{a}\x{d}\x{a} * [[\x{fffd} propos|index]]\x{d}\x{a} * [[Logiciels|software]]"...)
+called at /usr/share/perl5/IkiWiki/CGI.pm line 117 IkiWiki::decode_form_utf8(CGI::FormBuilder=HASH(0x2ad63b8))
+called at /usr/share/perl5/IkiWiki/Plugin/editpage.pm line 90 IkiWiki::cgi_editpage(CGI=HASH(0xd514f8), CGI::Session=HASH(0x27797e0))
+called at /usr/share/perl5/IkiWiki/CGI.pm line 443 IkiWiki::__ANON__(CODE(0xfaa460))
+called at /usr/share/perl5/IkiWiki.pm line 2101 IkiWiki::run_hooks("sessioncgi", CODE(0x2520138))
+called at /usr/share/perl5/IkiWiki/CGI.pm line 443 IkiWiki::cgi()
+called at /usr/bin/ikiwiki line 192 eval {...}
+called at /usr/bin/ikiwiki line 192 IkiWiki::main()
+called at /usr/bin/ikiwiki line 231
+~~~~
+
+so this would explain the error on cancel, but doesn't explain the weird encoding i get when editing the page... <sigh>...
+
+... and that leads me to this crazy patch which fixes all the above issue, by avoiding double-decoding... go figure that shit out...
+
+[[!template id=gitbranch branch=anarcat/dev/safe_unicode author="[[anarcat]]"]]
+
+> [[Looks good to me|users/smcv/ready]] although I'm not sure how valuable
+> the `$] < 5.02 || ` test is - I'd be tempted to just call `is_utf8`. --[[smcv]]
+
+>> [[merged|done]] --[[smcv]]