The solution is to generate a temporary app password from Twitter. In the "Security and Privacy" settings, there's a "Generate app password" button. Use that instead of your normal Twitter password in the authentication page inside Instagram and it'll work.
Thursday, December 03, 2015
I had some issues reauthorizing the Instagram app's access to my Twitter account because I have Twitter's two factor authentication turned on. The login page doesn't handle the authentication code Twitter sends me via SMS.
Tuesday, July 28, 2015
If you download MakeHuman for Mac OS/X and it won't open due to the error message:
"MakeHuman" is damaged and can't be opened. You should move it to the Trash.
The quick simple fix is to run the following from a Terminal session
xattr -rc /Applications/MakeHuman.app/