404 error when passing "cat" parameter to URL

Question

I encounter a strange problem with our WordPress site.

When I check the URL:

https://www.example.com/outlook-repair/

Everything is fine.

When I pass several parameters to the URL, for example:

https://www.example.com/outlook-repair/?os=Windows&param2=abc&param3=def

https://www.example.com/outlook-repair/?os=Windows

Both will be OK.

However, when I pass the parameter cat=xxx to the URL:

https://www.example.com/outlook-repair/?cat=Networking

I will get 404 not found error. It seems that only this parameter will cause problems. Why?

Answer 1

Probably WordPress gets "cat" as a category query and tries to load it. Tested in a project of mine and I also get a 404 error.