Hi,

The reporting engine in v18 builds dynamic groups and hierarchies based on account codes. Allowing special characters (like -) breaks the parser for ranges, intervals, and hierarchical structures. That’s why Odoo made this stricter — it simplifies grouping and avoids bugs in financial reports.

1-Recommended approach (adapt codes):

Replace hyphens with dots or numbers. For example:

    1000-01 → 1000.01

    2100-22 → 2100.22

2- If your client insists on using hyphens, you can override the constraint in a custom addon. Example:

from odoo import api, models

class AccountAccount(models.Model):

    _inherit = "account.account"

    @api.constrains('code')

    def _check_account_code(self):

        # Override: allow hyphens too

        for account in self:

            if not re.match(r'^[A-Za-z0-9.-]+$', account.code):

                raise ValidationError(

                    "The account code can only contain alphanumeric characters, dots and hyphens."

                )

Downside: You’ll have to patch the reporting engine as well, because the default grouping logic may not handle -. This means you might run into errors when printing general ledger, trial balance, or consolidated reports.

3- Keep the official account code in Odoo without the hyphen (e.g. 100001) but add a custom field for the “legacy code” with hyphens (for display/printing). This way you stay compliant with Odoo’s constraints, but users still see the familiar format on reports.

Hope it helps