Exporting org file breaks

Question

I have a similar problem to the one asked here Exporting org file breaks when upgrading to orgmode 8.3, org-mode cannot export org files and raises this error:

apply: Wrong type argument: listp, #("Peter's Emacs Config" 0 19 (:parent (#0)))

The solution aw has given works for me, that is, C-u M-x org-reload.

Nonetheless, I wanted to know why Emacs broke and how to fix such problems once and for all. Have not found anything on the Internet or on the GitHub page of org-mode.

I am using GNU Emacs 26.0.50.2 (x86_64-pc-linux-gnu, GTK+ Version 3.10.8) of 2016-10-26 and org-version 9.0.5.

Answer 1

1. The error message says that function apply raised an error because it expected a list argument but was passed a (propertized) string argument.

2. C-h f apply tells you that the last argument must be a list. It is likely that the last argument passed to apply is the string that is cited in the error message.

3. You can see more if you set variable debug-on-error to t and then provoke the error again. That will show you a backtrace of function calls. The backtrace will be more helpful if you first load the source code where the error is raised, that is, the *.el file, not the *.elc file, which is byte-compiled.

4. The backtrace will show you which function called apply erroneously. You can use M-x debug-on-entry FUN, where FUN is that function. That will open the interactive debugger each time function FUN is called. You can use d in the debugger to step through evaluation. Or you can use c to skip through an evaluation without going into its details.