New blogger interface and error when installing new template

Update : Blogger Fixed this error

The new blogger interface will be applied to all blog in next month . 
Some of you updated to new blogger interface and error message suddenly appear when installing a new template .
The reason is very simple . The error is on widgets in blogger and widgets inside template .




For example ,you added a Popular post widget to blogger when using old template . But in new template ,there's no Popular post widget in template itself . So error occurred.
What to do in this situation is to remove Popular post widget in Blogger and re-install later .
This is very different to old Blogger interface . The old one will show a dialog for all widget that not exist in new template and asking for keep these widgets or delete . We can still keep the old widget with all the code added in widget content .
So I recomment you to :
- Do backup before installing any template .
- Copy widget content .
- Remove all widgets
- Install new template
- Add widget back to template .