How do I resolve the error: The lookup file could not be saved

[waJesu]

I am trying to save a lookup file  in the Splunk App for lookup file editing and I get the error: The lookup file could not be saved. How do I resolve this?

[richgalloway]

Try again

Verify the lookup file permissions have not changed

Make sure no one else is editing the file

Make sure no other programs (outside of Splunk) have locked the file or have it open for exclusive access