iRule error - http_process_state_parse_header - Invalid state transition to ST_HTTP_XFER_HEADERS

hi,

 

 

When I have two iRules (an authenticate rule and an another rule), the following error is displaying

 

 

011f0008 http_process_state_parse_header - Invalid state transition to ST_HTTP_XFER_HEADERS

 

 

 

What does this error mean?

 

 

 

Cheers