table column 'cartData' can't save serialize() data

[iridance]

Returns a string containing a byte-stream representation of value that can be stored anywhere.

Note that this is a binary string which may include null bytes, and needs to be stored and handled as such. For example, serialize() output should generally be stored in a BLOB field in a database, rather than a CHAR or TEXT field.

reference php.net

The cartData column may change the type to blob or be processed to base64_encode/base64_decode before serialize/unserialize