Galera Cluster have some limitations, for example all tables MUST have primary key.
In recent version,
pxc_strict_mode is introduced to avoid unsupported features that can risk your data and server stability
One common trap is that SQL file exported with phpMyAdmin create index AFTER creating the table and inserting data.
During import, there is a transit state that table have no primary key and data need to insert to table, thus trigger the
#1105 - Percona-XtraDB-Cluster prohibits use of DML command on a table (database.table) without an explicit primary key with pxc_strict_mode = ENFORCING or MASTER