(This took a long time to research, so I'm answering my own question, hoping to save others some time)
Let's say I have a file like this:
one by two is $\froc1{2}$
When I run M-x org-preview-latex-fragment
, all I get is a white square indicating that something went wrong and in the *Messages* buffer the line:
Cannot find image file ‘/home/.../ltxpng/....png’
How can I view the error message?
texfrag
you get a menu item sending you to the error message buffer and one that is sending you to the LaTeX log file.