Having this error in my SharePoint Servers running Search Service Application.

This error was due to Search Index folder not granted FULL CONTROl permission to the following SharePoint Local Group

WSS_ADMIN_WPG

WSS_WPG

Go to your search index folder and grant them!

If you do not know how to find your Search Index folder. Run the PowerShell below in SharePoint Management Console

[sourcecode language=”powershell”]

##Change the name in case you are using a different name for the search service application

$ssa = Get-SPEnterpriseSearchServiceApplication "Search Service Application"

$ssa.ActiveTopology.GetComponents() | ? {$_.Name -like "IndexComponent*"}

## you should see able to see RootDirectory properties. and that is your search index location.

[/sourcecode]