This error code means the game could not save. Things you could try:
Save the game againEdit
Press S to attempt to save again. If it works, you can refresh the page.
Allow the game to use more memoryEdit
Right-click inside the game window and press settings. Switch to the middle tab if it is not open. Uncheck the "Never Ask Again" if it is checked. Press close and try to save again.
File a Bug ReportEdit
Only do this if all else fails, and we will get right on the issue.