1. POS Modules
Technical Changes in POS modules in the odoo 13 are given below:
1.1) account.journal is replaced with pos.payment.method, so you have to use it instead of account journal for payments.
1.2) In pos order statement_ids replaced with payment_ids and the relation is with new object pos.payment.
1.3) Major changes in create_from_ui() and _process_order().
1.4) pos Ticket change as Order Receipt widget.
1.5) stock_location_id remove from pos.config.
1.6) cash.box.in object removed for pos.
2. Website Modules
Technical Changes in Website modules in the odoo 13 are given below:
2.1) sale_get_order() is changed.
2.2) website.redirect model removed, now only use website.rewrite.
2.3) website_published, auto_confirm is removed from payment.acquirer.
2.3) Image field is replaced with image_128 in payment.acquirer.
3. Back-end Modules
Technical Changes in Back-end modules in the odoo 13 are given below:
3.1) @api.multi, @api.model_cr and @api.one removed.
3.2) view_type is removed.
3.3) args from cron xml is removed.
3.4) is_customer, is_vendor removed, in place of that use, context="{'res_partner_search_mode': 'customer'}" or context="{'res_partner_search_mode': 'supplier'}".
3.5) In act_window, src_model is replaced with binding_model.
3.6) residual_signed field is replaced with amount_residual_signed.
3.7) residual field is replaced with amount_residual.
3.8) date_invoice is replaced with invoice_date.
3.9) date_due is replaced with invoice_date_due.
3.10) account.move.line just link with invoice_line_ids its automatically create line_ids. number field is removed from invoice
3.11) number field is removed from invoice