Unable to add users to a group Sharepoint permissions

I worked on one of the issue wherein I was unable to add Users to ANY of the group, even though we were having 3 groups on the Site.

Here is what I did to resolve the issue. Hope this steps will help you solve your issue Quickly J

Whe we go to Advanced permissions, You can see that there are already 3 Groups added with different permission levels.



From Advanced permissions page click on New – Add user- It takes us to the page where we can add the user explicitly or inside a Group. In this case, "Add Users to SharePoint Group" option was grayed off - (Above 3 Groups are not visible)




After some investigation I found that, those groups were removed from the Groups – Quick launch




To add them back – Click on the Groups – Settings – Edit Group Quick Launch – Add these 3 Groups there and say Okay.




Once these 3 groups are visible Under the Quick Launch – Click on New – Add user.




Issue is resolved now; you can see the groups in the drop down as expected