Magento2: Cannot access backend - Exception #0 (Exception): Notice: unserialize(): Error at offset 4161 of 7401 bytes

[akamura]

Preconditions

1. Magento 2.1.1

Steps to reproduce

I needed to delete the database and restore it from a mysql dump file in development mode.
After that I did:

1. php bin/magento setup:upgrade
2. php bin/magento cache:clean
3. php bin/magento cache:flush
4. php bin/magento setup:static-content:deploy

Expected result

1. Open the backend

On the frontend everything is fine, just the backend is affected.

Actual result

[akamura]

If I empty the "extra" column in admin_user table in SQL I can login again successfully from backend