[TYPO3-english] Problem with upgrade: Your browser version looks incompatible with this TYPO3 version!

[Bert Hiddink [BENDOO e-work solutions]]

Hello,

A client was using an old version of TYPO3 (4.3.x) and suddenly got this 
error when trying to log into the Backend:

"Browser error

Your browser version looks incompatible with this TYPO3 version!"

So I decided to upgrade first to a 4.5 LTS version (4.5.36).

However, when trying to log into the BE, I still got this error:

"Oops, an error occured!

Browser Error: Your browser version looks incompatible with this TYPO3 
version!"

 From what I remember this error was due to a hardcoded browser version 
(MSIE, Mozilla, etc) but was resolved a long time ago.

How could this problem still come up with 4.5.x LTS? Any ideas/suggestions?

Thanks in advance!

Regards,
Bert