Update : I found you can avoid making this change to your database by changing where uploaded attachments are cached.

Just changed WebUploadCacheModule in Core::Web to FS instead of DB.

Justin

On Thu, Feb 25, 2010 at 9:13 AM, Justin Noel <otrs@jandgnoel.com> wrote:
I was running into a problem where uploading attachments to a ticket failed.  Instead of getting a warning after waiting for the upload, the page would just refresh and the attachment would not be there.

I thought updating the WebMaxFileUpload setting in Config Options: Framework -> Core::Web would solve the problem.  It did not.

I finally found this warning in the Apache error log file : 

ERROR: OTRS-CGI-99 Perl: 5.8.8 OS: linux Time: Tue Feb 23 13:46:31 2010

 Message: Got a packet bigger than 'max_allowed_packet' bytes, SQL: 'INSERT INTO web_upload_cache  (form_id, filename, content_type, content_size, content, create_time_unix, content_id) VALUES  (?, ?, ?, ?, ?, ?, ?)'

The final fix is that the max_allowed_packet in your MySQL my.cnf file must ALSO be set to whatever you want the max upload size to be.  Here is my sample : 

max_allowed_packet = 16M

Hopefully this tip will help someone else.  I found several people asking this question with responses like "This has been answered many times before...." .  Well, I never found an answer.

Justin Noel