Getting a mystery error or undescribed failure when publishing to Map Server or MapGuide? It could be that you are hitting IIS' default upload limit of 30 megabytes. Now, that's a compressed 30 mb, so it likely won't happen unless you are pushing quite a lot across.
To change the limit:
- Open the IIS Manager
- In the main window, double click Request Filtering
- Right click anywhere, and select Edit Feature Settings.
- Change the Maximum Allowed Content to a larger value
No restart of IIS should be needed.