MYSQL5.5 supports utf8mb4, and MYSQL5.1 does not support “utf8mb4”.

When connecting to the database, if utf8mb4 is specified, the error code that will appear is:

Error 1115: Unknown character set:’utf8mb4′

There will be utf8mb4 incompatibility.

So if you want to use utf8mb4 to store emoji characters, please upgrade as soon as possible