Parse error: using Search Engine Optimization MOD for PHPBB

When correctly installed it causes no error unless you have other modified code that is incompatible.

If the former, you need to correctly install it.

If the latter, I can't support other people's code because I am usually not familiar with it and do not have the time to become familiar with everyone else's code.

We used your instructions to replace the code, which is the cause of the error. No other code is modified, as this is a fresh install, that worked perfectly prior...

Well, ya did something different from the many thousands who have installed it and who didn't get the error.

Try removing it and doing it again, and you may find that you simply made a small error.