403 Forbidden When Uploading Tracking Details To Sytist Website

We've just moved our sytist installation to a new server host and also renamed our subdomain installation (store.canvasfineprint.com) to base (canvasfineprint.com.au).  We re-named all instances of the old name to new in the sql database and all is working fine.  However, we are trying to upload tracking details for an order and receive the 403 forbidden error.  Where do we look - permission of file .htaccess etc? thank you.

ps.  I'm not seeing any error logs generated server side to help with the issue - what should I be checking to ensure the error reporting is set correctly?

403 error is usually caused by triggering mod security on the server  (or ModSec). Mod security is good but also has false positives. 

Tim,

We would like to thank you so much for quickly and accurately pointing us in the right direction for the 403 error on our website.  Saved us hours of debugging time on our end! So, when we immediately contacted our hosting company, they identified the rule that blocked the request that resulted in the 403 error and the rule has now been disabled by them. (note: It did not show up in the initial checks as they first had to identify the requesting IP address - the one from our internet provider.)  The website is now functioning perfectly with our new hosting provider!

Thanks Again - here's hoping this post also helps someone else from pulling their hair out, if they have the same issue !