In Chamilo 2 we passed all the tables from utf8mb3 to utf8mb4 except the version table because if we changed it we got the following error :
An exception occurred while executing a query: SQLSTATE[42000]: Syntax error or access violation: 1071 Specified key was too long; max key length is 3072 bytes
This is because the version.version field is of type varchar(1024) and passing from utf8mb3 to utf8mb4 use more bytes per caracters.
To avoid this kind of issue we should change version.version field to type "text".