Hi,
Google+
I have tried to register an account and works, try to clean your browser cache
Instagram
this problem is not related to instagram but to option "Social Login Type" set to "Redirect", I know, you have this parameter set to "Popup" but instagram does not support popup login, so it force for only for instagram login with "Redirect".
I will explain you better with a simple example: if you set parameter "Social Login Type" to "Redirect" then also Facebook, Twitter, Google and Linkedin will not works and you will have also for this provider same error.
Why? This is a Bug?
Yes and No, this behavior is due to a combination of following causes:
- htaccess configuration (probably due to Admin Tools)
- 404 error on page (you have many errors in all your page and this is not caused by our products)
- Social Network plugin, parse all URLs because this is a plugin, so it parse also 404 errors and set this as redirect uri
Fix?
Of course, we have already fixed this on your site, and we will apply this fix in next release.