I am trying to close a session in Odoo 13 but I am getting the following error 

I checked the log file and found this:

2023-05-16 14:11:39,382 1484292 ERROR Gofresh_Live odoo.sql_db: bad query: INSERT INTO "account_payment" ("id", "create_uid", "create_date", "write_uid", "write_date", "amount", "communication", "currency_id", "journal_id", "move_name", "name", "partner_id", "partner_type", "payment_date", "payment_difference_handling", "payment_method_id", "payment_type", "state", "writeoff_label") VALUES (nextval('account_payment_id_seq'), 2, (now() at time zone 'UTC'), 2, (now() at time zone 'UTC'), '2.300', 'POS/06001', 96, 7, NULL, 'POS/06001', NULL, 'supplier', '2023-05-16', 'open', NULL, 'outbound', 'reconciled', 'Write-Off') RETURNING id
ERROR: null value in column "payment_method_id" violates not-null constraint
DETAIL:  Failing row contains (3325, POS/06001, null, null, null, reconciled, outbound, null, supplier, null, 2.300, 96, 2023-05-16, POS/06001, 7, open, null, Write-Off, null, null, 2, 2023-05-16 14:11:35.362199, 2, 2023-05-16 14:11:35.362199, null, null).
 
2023-05-16 14:11:39,386 1484292 WARNING Gofresh_Live odoo.http: ('The operation cannot be completed:\n- Create/update: a mandatory field is not set.\n- Delete: another model requires the record being deleted. If possible, archive it instead.\n\nModel: Payments (account.payment), Field: Payment Method (payment_method_id)', None) 

I enabled split transaction before opening the session and now I can't turn it off as its asking to close the session first.

Can anyone tell me how to resolve this?