404 error

I dont know if this is the correct platform to post this issue, if not please forgive me. I am very novice with FB apps, but i’ll try to explain my problem as clearly as possible.

I have created 3 same type of apps for my website. They were running perfectly 2 weeks ago. From this last 2 weeks im facing this weird problem. When an user adds my app to one of their pages and starts installing it in the profile, then if they are logged into that business page then the first step of the application never comes and it gives me a 404 error. But however, when i switch back to my original profile and try installing the app, it comes fine. Moreover, this issue wasnt there before as i stated previously. It developed only recently.

Does anyone have any idea a to what is causing this error to occur? Has FB changed anything internally for which i need to change my code too?

I hope that you will understand my issue.

Thanks a lot in advance!!!

Facebook is renowned for changing their API, check out their changelog and/or notices on their developer support pages.