Error displayed in web browser when "markdown-preview-mode" is run

[jtongen1]

I have not been able to get this working correctly. I've customized my markdown-command, and when I run markdown-preview I get a markdown displayed in my browser.

But, when I run markdown-preview-mode, the following is displayed in my browser:

Caught Error: (wrong-type-argument stringp nil)

The URL is set to: http://localhost:9000/?uuid=ef199220-c8b3-42f8-8d82-5eeb4ad96966
(or similar)

I'm using the following for my markdown-command (and its in the path): python -m markdown