I don't understand the above error. When I try to start a drill session on my current buffer, the message org-drill: invalid match tag "" appears.

I tired to customize the variable org-drill-match in the customization menu:

I tired to set it to nil, to a tag string like this: tag or "tag" or ":tag:" or "\:tag\:" but it doesn't change anything, where <tag> is the tag I choose.

I also don't find the string "Invalid match tag" in the org-drill.el file.

How can I reset the org-drill-match variable so that the drill session works again. Or is there another reason for this error, maybe a badly formed tag?

  • I'm having the same problem after upgrading org-mode to 9.2. :-( There are several breaking changes that might be affecting org-drill. My guess is org-get-tags, which org-drill uses, but I haven't … drilled into it.
    – amitp
    Commented Jan 5, 2019 at 17:05
  • @amitp This was probably the problem! I rolled back the latest update and the problem disappeared.
    – chriad
    Commented Jan 6, 2019 at 9:10

2 Answers 2


There seems to be some incompatibility with org 9.2

Workaround: find org-drill-hide-subheadings-if in org-drill.el. Change the "" to nil.


Something with your org-mode installation is messed up.

I have run into this annoying problem several times. I use a combination of use-package and straight.el for installing packages, and the only thing that sorts the problem is to wipe out all the packages, reinstall and rebuild.

Of course straight.el and use-package make this very easy and efficient. But that is the only thing I found that solves the issue.

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