The post processing stack will not work, no workarounds so far have worked.
I’ve exported the project and then imported it in a new one, tried the stack in a new project, old projects, updated Unity to the latest version, renamed the script, copied the content of the script and deleted the old one and then pasted it into a new one and made certain the names were exactly the same (it was made by Unity, so it should’ve been), deleted the asset and redownloaded it—everything everyone has stated might work going back at least 6 years.
Nothing works. It just gives me a warning in the inspector about “No MonoBehavior scripts in the file, or their names do not match the file name”, and gives the aforementioned error when dragging the PostProcessingBehaviour.cs script onto the camera.
Is this not a script written by Unity? How is it not compatible with (multiple versions of) Unity?
Aaaaand now it says “can’t add script behaviour MaterialFactory.” whenever I drag the PostProcessingBehaviour script onto the camera.
I don’t know what “MaterialFactory” is, but I am 100% positive that I am not trying to add its script anywhere, especially since I don’t even know what or where the hell it is.
I should note that literally nothing has changed since I made this post except for restarting Unity. Apparently that made things even worse.
After falling asleep briefly and waking up, I found the issue to be the current version of the post processing stack that is currently in the asset store.
So for anyone having this same issue, just go to Window>Package Manager and check the post processing stack from there, that is the latest one and should work without issue if you are using 5.4 or above.
What you said to try didn’t work for me. What I did was delete all the scripts from the asset pack that the console said were causing errors. I didn’t need them anyways because I only needed the PostProcessingBehaviour script and now it allows me to add it to the main camera.