"Theme could not be found. Test Defaulting to Classic." after update skuid version to "12.2.8"

I have update Skuid to version “12.2.8” in the Salesforce sandbox. and its showing error “1. Theme could not be found. Test Defaulting to Classic.” and also there is no option of “Update Out of date Theme” under the theme tab

I just updated to 12.2.12 and I discovered the same issue.  After looking into the XML I see the pattern.  If your page theme is set to Default:  

The XML states:

<skuidpage showheader=“true” personalizationmode=“server” showsidebar=“false” theme=""

Notice the theme just = double quotes.  This is what is throwing the error.

If however, you switch it to classic and save.

The XML will switch to theme=“Classic”

If you then switch it back to Default and save.

The XML Theme= goes away completely.  So default does not include Theme=.  

 To fix the error go to any page that has the error and switch the page from default to another theme, click save, and then switch it back to default and it will be fixed.  Keep in mind that page includes that contain this error will have to be fixed as well.