Mojave upgrade has broken Spotlight index for Mail.app

I had exactly the same problem after upgrading to Mojave and I have found a solution that hopefully should help you and others.

The problem here is likely caused by one or more obsolete Spotlight plugins. In particular, I had an old plugin installed called "_TagsMail.mdimporter" from CASEapps that was causing the mdworker task to crash when it tried to index the ~/Library/Mail folder. When I removed the plugin and restarted my Mac, the Spotlight indexing started working again. I suspect the mdworker tasks are now sandboxed in Mojave and the old plugin doesn't work correctly with sandboxing.

The steps to follow are:

1. Remove any obsolete plugins from ~/Library/Spotlight - especially "_TagsMail.mdimporter" if it's there

2. Also check /Library/Spotlight for any old plugins that haven't been updated recently

3. Restart your Mac

4. Now if you enable Spotlight indexing it should work

After I found the cause I searched and found this same issue described on Matthias Nott's blog:

https://www.mnott.de/_tagsmail-mdimporter-prevents-spotlight-in-mojave-to-finish /

I hope this solution works for you!

My Spotlight has also been ruined since upgrading to Mojave. So far Apple had had me repair all my permissions, I've re-indexed in every possible way, I have removed all the old plugins from my spotlight library, I have unchecked the Bookmarks & History box on the Spotlight preferences and I have also reinstalled Mojave.

Spotlight still only works intermittantly. Something keeps breaking it.

Has anyone got any idea at all about what to do next!

I suspect this is probably caused by a hidden setting that allows the full path to be displayed in the title bar of Finder windows. You might have previously used a utility like TinkerTool (https://www.bresink.com/osx/TinkerTool.html) to change this? If so, downloading TinkerTool is probably the easiest way to change it back. See the "Show selected path in window title" setting on the Finder page.

The setting can also be changed from the command line in Terminal - see this web page: https://www.tekrevue.com/tip/show-path-finder-title-bar/

Hope that helps!

While the original issue in this thread related specifically to the Mail app, it sounds like you have a more general problem with Spotlight? What is it that you are seeing that is only working intermittently? More specifics about the problem would help.

In general the first step is to understand whether the Spotlight index is being built successfully.

1. If you click on the Spotlight menu and type in some text, do any results show up?

2. When you type in some text, is there an Indexing progress bar at the top of the top of the Spotlight results window? (Similar to http://www.extensions.in.th/amitiae/2014/prefs/images/spot_1.png)

If the index has finished building successfully there should be no indexing progress bar and there should be multiple results found in different categories.

Depending on the answers I may be able to suggest further things to check.

My problem is that spotlight will work fine for a bit but then stops working normally. If you then search for something it can take about 2 minutes before the searches come back. During that time the spotlight search bar displays no results and has a greyed out no parking type sign on the right hand side. Never used to do anything like that before Mojave upgrade....