When I hit M-r to get an exact match, helm-projectile-recentf, I get:

Debugger entered--Lisp error: (cl-assertion-failed ((and (file-exists-p file) (string-match (image-file-name-regexp) file)) "Can't rotate non image file"))
  cl--assertion-failed((and (file-exists-p file) (string-match (image-file-name-regexp) file)) "Can't rotate non image file" nil nil)

I have no idea what that's supposed to mean;) Any pointers?;)

1 Answer 1


The error message is telling you that you've tried to rotate a file that is not recognized as being an image file.

Turn on debugging: M-x set-variable RET debug-on-error RET t RET, and check the resulting debugger backtrace, to see what went wrong.

You can step through the execution of whatever function raised the error, using debug-on-entry. For example, if you want to step through helm-projectile-recentf, then use M-x debug-on-entry RET helm-projectile-recentf RET. Then, when that function is called you'll enter the Elisp debugger, and you can step through it with d to see what it didn't like.

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