We've found the same issue on the Updates page under the Server Admnistration section as on the Transports page, namely the following:
We're using the free version - since updates via web interface aren't supported in the free version, we didn't expect it to function, but just letting you know about the error.
Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request.
Please contact the server administrator, postmaster@spamguard.fswinc.org and inform them of the time the error occurred, and anything you might have done that may have caused the error.
[3092]ERR: 32: Warning in Perl code: Bareword found where operator expected at /var/www/proxmox/server/updates.htm line 19, near ""<p style='margin:10px'>" __"
[3092]ERR: 32: Warning in Perl code: (Missing operator before __?)
[3092]ERR: 24: Error in Perl code: syntax error at /var/www/proxmox/server/updates.htm line 19, near ""<p style='margin:10px'>" __"
Apache/1.3.33 Ben-SSL/1.55 (Debian GNU/Linux) mod_perl/1.29 HTML::Embperl 1.3.6 [Thu Apr 13 12:36:26 2006]
We're using the free version - since updates via web interface aren't supported in the free version, we didn't expect it to function, but just letting you know about the error.