Installed the dev module to my D8 dev site (8.1.0) to try it out. After deciding i didn't want to use the module anymore, i attempted to uninstall the module only to be presented with an error 500 on the module uninstall page.

Checking apache logs this is the output:

Cannot instantiate interface Drupal\\Core\\Cache\\CacheBackendInterface in /core/lib/Drupal/Component/DependencyInjection/Container.php on line 268

Not sure what this module has done, but its made any other modules uninstallable with it.

Any quick fixes?


MattMeadows created an issue. See original summary.

MattMeadows’s picture

Issue summary: View changes
kclarkson’s picture

after install I received the following error.

Call to undefined function variable_del() in modules/admin_menu/admin_menu.install, line 22

I commented out the lines but that was given the error

Cannot instantiate interface
Drupal\Core\Cache\CacheBackendInterface in
line 268

After deleting the module and doing a CR the error went away.

awasson’s picture

There is a good howto for uninstalling it here:

Further to that I was receiving an error/warning that wouldn't go away, indicating that Drupal was looking for a node_counter table which was a remnant from the old Drupal 7 version of Admin Menu. I simply added a new empty table that looked like the Drupal 7 node_counter table. More info about that here: