Q:

Server error: The URL is invalid. It may refer to a nonexistent file or folder or refer to a valid file that is not in the current Web

When checking out the Home.aspx page I receive this error. 

Server error: The URL is invalid. It may refer to a nonexistent file
  or folder or refer to a valid file that is not in the current Web

I have read and checked the log files based on this article and we are not having any issues with disk space.
The file is checked out (even though it isn't initially indicated) and all of the webparts go missing. It happens both in the designer and from the web interface. I am really at a loss as to what to do to fix this issue, any suggestions would be greatly appreciated.
Thanks!

A:

This is most probably happen in following case. Please check some checkpoint to solved this error:

SharePoint Database Server should have minimum 1 GB free space.
SharePoint Site application pool user/password is not expired.
Reset IIS and Recycle Application Pool of SharePoint site.

This will solve your error.

