Ever did a Site Collection backup either from CA or PowerShell, and interrupted it for some reason! and found your site still on the read only.
I faced this issue with a customer whom we decided to cancel the backup now and do it in later time. Interrupting it caused the site to remain for sometime in readonly, although we wrote the PowerShell to do unlock
Set-SPSite -Identity “<SiteCollection>” -LockState Unlock
Still the Site Collection was in ReadOnly mode.
After investigation, we ran the ClearMaintenanceMode
$Admin =new-objectMicrosoft.SharePoint.Administration.SPSiteAdministration('URL')$Admin.ClearMaintenanceMode()
Now try to called it and check or confirm the value
$site.MaintenanceModeTrue
And it was back to Normal state..