1. First, make sure you've selected at least one photo in the filmstrip. If you have no photos selected when you invoke Map > Tracklog > Auto-Tag Photos, then LR can give that error. See this bug report: Lightroom: Auto-Tag Photos produces "Unexpected error" | Photoshop Family Customer Community
2. If you're still getting the error even when there are photos selected in the filmstrip, try using the menu button in the toolbar at the bottom of the Map module:
Great, you got it!
Idea 1 fails:
I did exactly as your advise. Today there is no error message but unavailable gray Menu-entry "Auto-Tag Photos".
Idea 2 works:
My toolbar was hidden, so I didn´t know about it. This way is working well and that´s the finaly solution to me.
After auto-tagged photos via Idea 2, I deleeted GPS-Positions from all photos and tried again way as Idea 1.
But either I select one or all photos in the strip, the Menu Map > Tracklog > Auto-Tag Photos still stays unavailable (gray).
Looks like a mustake, anyway ...
thank you well and good luck!
Please add your me-too vote and details of your configuration to the bug report I linked to above. That will make it a little more likely Adobe might eventually fix the bug.