I had the same issue, and I solved it by connecting first the Instagram account, which worked flawlessly, and only after that I connected the Fabook account, and it also worked without anymore errors.

Thank you, this solved the problem!

I'm encountering the same error while testing Odoo 

I'm Having the Same issue. Is there a work around or fix yet? 

I'm having the same issue, my pages doesn't have instagram account or has been connected to instagram before. And we can't connect our pages to oddo, we're about to get a subscription, but since this trial isn't working for us, I'm really not sure if we're gonna go with it. Hopefully there's a solution. We've been working to connect it for the past hour, and nothing worked.

Same issue here. Connection goes smooth but then after confirming we get the same message. We'll check permissions on Facebook Page and Business manager and such since there are layers of roles and users within Meta, and might be a Facebook thing.

Edit: it has to do with meta taking over the admin status of the page, as soon as you connect instagram it removes us from the admin on the page and uses the meta business manager, and odoo sees the empty admin list on the facebook page (at least in our case).

trying to go around it atm

Edit2: Sort of solved. It's due to Facebook Page and Meta Business Manager. As soon as you link your Instagram, you are removed from the visible admin list on Facebook page, and added on the meta business manager admin, along with the control of the page. Odoo does not see the meta business admin layer from facebook, I guess another integration system is required. Facebook is a mess though, it's full of issues, but we found a workaround:

You need to add another admin to the page, and THAT admin has to set up facebook and instagram on Odoo. Note: We had to add another admin via mobile app, it could not find anyone to add on the desktop version of Facebook. Terrible.

Now everything is set up, double admin on facebook page, first of them links the instagram account and becomes the meta business manager admin of both. Second admin syncs up odoo.

I'm having the exact same problem!  Is this a bug?  First time using the system, and already having major headaches.