So a page has been sending errors for long, but we weren't able to find any way to debug it, no error code, and I don't have the authorization to see the logs so I had to wait for a co-worker to be back from holidays.

Now that they're here, I could have a chance to find what was the error.
And be really annoyed about it.

The error was provoked because the security system found a tautology in the data I sent.
(I send datas to build the page, and one parameter is called "Page". Since it was a page of management, I've sent "Gestion", which is management in French. So I sent "Page=Gestion", the security saw "ge=Ge" in it, poof, tautology, you shall not pass.)

That is so ridiculous.