The other question I have for all of you is do you have the lvl CC required to do the new walls?  After the last maintenance some buildings will show that they can be upgraded, when in fact they can not as the CC requirement of other building requirements have not been met.  This Will result in several red box errors including 2191 and 2181 snowbear errors.
If you have not met the building s requirements to upgrade any building including walls, and it still 'appears' to give you the option to do so, and you get the error, then you need to check to see if you have in fact met the building requirements of your other buildings before you try to move forward.
The team is aware that it 'appears' for many players that they can build and/or upgrade something in their bases.  This is a visual issue that will be fixed on the next maintenance.