Blackfriars: "Seek Assistance 105" barrier code

[itsjamierawr]

The other day I decided to jump off my Canterbury West - Charing Cross train at London Bridge and get on the Bedford bound train behind to get to Blackfriars (closer to where I was meeting my friend). I had checked through various journey planners that my Canterbury West - London Terminals ticket was valid (which it was as they all showed the same ticket covering that route).

Anyway, I put it into the barrier at Blackfriars and I got a "Seek Assistance 105" message, thankfully the barrier staff just glanced at it and let me through but this lead me to wonder what that error is (I did try google, didn't help) and if it is actually valid, if so what other London Terminals/routes can I go (besides London Bridge, Cannon St, Charing Cross, Victoria) on a Canterbury Stns - London Terminals (Not HS1) ticket?

 

[Olympian]

On Cubic gates, code 105 means "Invalid TOC type ticket".

 

[furlong]

Exactly what ticket type was it?

I see this error from time to time when using a particular ticket type at a location where the main train operating company does not issue tickets of the same type for use on its own network.