Running Doxygen (1.7.4, Ubuntu 11.10) over one of the larger PHP applications we use at PANmedia, I ran into this error:
Error: dot: can't open /var/workspace/app/documentation/html/class_a_d_o_d_b___data_dict_a4ad217393b4e364e233cc70336d93ae8_cgraph.dot
Experimentation led to the following solution: switch DOT_CLEAN off, either via the Doxygen GUI (pictured) or directly in the Doxygen configuration file.
DOT_CLEANUP = NO
What does this do?
If the DOT_CLEANUP tag is set to YES (the default) Doxygen will remove the intermediate dot files that are used to generate the various graphs.
I recall running into this error over a year ago (last time I used Doxygen), and it wasn’t until I stumbled onto the solution that I remembered solving it in the same way last time.
Documenting the solution here means that next time I use Doxygen after a long time away, I won’t have to repeat the process.