I've two db odoo v14. One online on odoo cloud and one premise on self hosted.

1 - On premise, i want to use json.dumps() function. I got name 'json' is not defined.
    I pip3 check, no broken , and python version 3.7.3. pip3 simplejson 3.16.0

    I'm running on debian buster.

    In console, running python3 command i do import json and can do json.dumps() 

    I write my script in odoo dev mode, going to technical->cron actions. I cannt import.

    I got forbidden opcode. 

2 - On online db, i already use json.dumps() without import in same way using odoo dev mode.

How can i use json with premise db?