What could be the problem with DB connection on Amazon server?

Question

MySQL

Strange things are happening...

There is an application on JS + PHP + WP, after transferring to Amazon, records are no longer made to the database, but not quite, records are entered into one table 'activity' (the same database) perfectly, but not in others , there are also 3 almost identical tables with the same code, but you can make changes to 2 (not new records), but not to one.

There are no connection errors, data is not entered.
Where to dig?

Answer 1

Go to phpmyadmin select database > SQL and run
SET @@global.sql_mode= 'NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION';
the problem is that new versions, when writing to a qveri table, in which instead of int there are empty '' in the new database 5.7.12 - MySQL does not auto-fill with zero.

Answer 2

see what error the insert gives