Upgraded to 5.7.5.9 now can't edit anything

Permalink
Hi,
I recently upgraded a site to 5.7.5.9 by copying the new concrete folder into updates folder and running the upgrade, everything seemed to go well but now i can't edit any blocks (tried multiple browsers)

The site was fully functional prior to the upgrade.

The only console error i get is;
underscore.js:1 Uncaught TypeError: Cannot read property 'replace' of undefined

Any help to fix or revert would be appreciated

 
Area55 replied on at Permalink Reply
Fixed this.

Wasn't the upgrade at all, prior to the upgrade i added a block within an <a> tag.
Apparently this is bad.