Why they don't like each other

I'm running on a Multi-Site-Network and have Facebook logins enabled on both sites, but the use of these two services apparently comes with an issue when used together…

Due to Facebook restrictions, each APP ID can only support logins from a single domain. Creating a second APP ID for the second site just "duplicates" the user and adds a (2) to their username.

I've come to the conclusion that my only options at this point are:

• Drop support for accepting Facebook logins altogether
• Drop support for operating on an MSN
• Drop Facebook support on only one of the two

Frankly I don't like any of those options. I've created my MSN's around the ability to accept Facebook logins, and I need to be able to run two communities also.

Maybe there's another option? I'm open to suggestions.

It may be possible:

Facebook login with multiple domains - Stack Overflow

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Other possible workarounds, which both require an experienced developer:

1. Recode the login system to work via a shared domain and syndicate cookies
2. Change Facebook login to an unoffiical oAuth based login rather than Facebook Connect (I'm not sure if this would avoid the problem or not, but could also be done in tandem with suggestion 1)

Thanks Chris,

I did what it said on Stack Overflow, and so far it seems to be working. I suspect it might stop working in the future though, as the tutorial shows adding a "mobile website URL" – which Facebook claims to be getting rid of in July. I don't know if that's this upcoming July or the past one, but current it does work…for now.

Guess I'll cross that bridge when the time comes. Thanks Chris!