Issue Description
Recently I was trying to add a site collection administrator to a site and I got the belowmessage
You need to be a site collection administrator to set this property. at Microsoft.SharePoint.ApplicationPages.ManageSiteAdminPage.BtnSubmit_Click(Object sender, EventArgs e)
at System.Web.UI.WebControls.Button.OnClick(EventArgs e)
at System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument)
at System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument)
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
I was already the site collection administrator to the site and it did not make any sense.
Fix
On further trouble shooting, I found the solution for this.Browse to Central Administration - > Site Collection Quotas and Locks.
The options available here are:
Not locked
Adding content prevented
Read-only (blocks additions, updates, and deletions)
No access
This site collection was in Read-only status. Unlock it (Change the status to "Not Locked")
