Hello! I am experiencing the same issue while trying to export an .svg file as a .pdf. 

I'm not a mac user, but we can get the ball rolling here. Please:

1. Describe the source of the file: created with Inkscape, downloaded, imported from another program, etc.
2. Describe the specific steps you took, the result you expected, and the result that actually happened.
3. Describe your OS (your computer's Operating System: Mac/Windows/Linux/etc. & version).
4. Describe if Inkscape was newly installed, or upgraded from an earlier version.
5. Describe the version of Inkscape and the installer you used (the file you downloaded from the website: .msi/.exe/.zip/other ). 
6. Describe any special hardware being used, like tablet/stylus or multiple monitors.
7. Describe any helper/assistive programs or keyboard modifiers (macros, languages, etc.).

Answers to these will help an experienced Mac user assist.