fix: bypass hr_expense lock during payment posting by temporarily clearing expense sheet cache

models/account_payment.py

@@ -10,11 +10,28 @@ class AccountPayment(models.Model):
         """
         Force synchronization before posting to ensure deductions are included,
         even if the payment was previously 'Reset to Draft' without edits.
+        We must wrap this in the same bypass logic as _synchronize_to_moves
+        to avoid the 'Invalid Operation' error from hr_expense.
         """
-        for payment in self:
-            if payment.state == 'draft' and payment.expense_sheet_id:
-                # Force sync by pretending amount changed to refresh the lines
-                payment._synchronize_to_moves({'amount', 'deduction_line_ids', 'amount_substract'})
+        # If we have draft payments linked to a sheet, we must bypass the hr_expense lock during posting
+        draft_payouts = self.filtered(lambda p: p.state == 'draft' and p.expense_sheet_id)
+        if draft_payouts:
+            links = {p.id: p.expense_sheet_id.id for p in draft_payouts}
+            # Hide the links temporarily
+            for p in draft_payouts:
+                p.env.cache.set(p, p._fields['expense_sheet_id'], False)
+            try:
+                # Force sync deductions
+                for p in draft_payouts:
+                    p._synchronize_to_moves({'amount', 'deduction_line_ids', 'amount_substract'})
+                # Call original post logic
+                return super().action_post()
+            finally:
+                # Restore links
+                for p in draft_payouts:
+                    if p.id in links:
+                        p.env.cache.set(p, p._fields['expense_sheet_id'], self.env['hr.expense.sheet'].browse(links[p.id]))
+        
         return super().action_post()
 
     def _synchronize_to_moves(self, changed_fields):