Gary Kuhlmann - August 25, 2017
Currently, it seems anyway, a lot of the underlining technologies that I use everyday to build websites (ie, PHP and MySQL) are quickly upgrading and making big changes. These changes are exciting and I look forward to utilizing them as soon as I can but sometimes it is hard to just “flip the switch” on a major update so I tend to migrate each site over one by one to make sure everything is still working and performing well. To this end, I am now running a hybrid setup where I use MySQL 5.6 on some servers and MariaDB 5.5 on others. Migrating between the two mostly works just fine but lately I have started encountering an issue with collation and character sets as 5.5 does not support some of the settings that 5.6 does. Here are my notes on how to fix this issue:
Source: https://wordpress.org/support/topic/1273-unknown-collation-utf8mb4_unicode_520_ci/