HTTP header: buffer full

This error is related to incorrectly processing DEFLATE compression in an HTTP flow, it looks like it can happen in several different ways depending on how the content is put together (compression, encoding, what profiles are applied to the vs, character set, etc). It may just be corruption, a non-standards-compliant server, or someone intentionally mal-forming their HTTP to try to trick a content filter or cause problems. BIG-IP has very strict checking of a lot of different aspects of HTTP while it's proxying requests/responses.

I'd suggest to ignore it if it's not causing problems, or to open a support case with a decrypted packet capture if you can reproduce it and are interested to see what exactly is the problem (or f5 TMM bug) with your sample.