The symptoms are:

Users find they cannot open PM's and get a Server Error - usually like this:

Quote:


You may have made NO changes to your YaBB settings to have this occur. It can also occur when you move to a new host.  The new host may be using different settings on mod_security.


The issue is likely a tightening of security by the ISP/Webhost.

There are two equally good approaches -

A. - Check with your webhost and see if 'they' can fix this for you, usually possible with some encouragement.

http://www.yabbforum.com/community/YaBB.pl?num=1251304495

B. - Deti has written a workaround for the issue:

Edit the ./Sources/Subs.pl file and search for this:

&image_resize;
# Start workaround to substitute all ';' by '&' in all URLs
# This workaround solves problems with servers that use mod_security
# in a very strict way. (error 406)
# Take the comments out of the following two lines if you had this problem.
# $output =~ s/($scripturl\?)([^'"]+)/ $1 . &URL_modify($2) /eg;
# sub URL_modify { my $x = shift; $x =~ s/;/&/g; $x; }
# End of workaround
if ($yycopyin == 0) {
 

Remove the highlighted characters. Then save the file back on your server.