Hi,

The "read access to res.users" error during login, despite granting read access in ACLs, often stems from the login process requiring more than basic read permissions. Odoo needs to access specific fields and methods on res.users for authentication and setup.

Troubleshooting involves checking ACL inheritance (ensuring your group inherits from base.group_user), reviewing record rules for undue restrictiveness, identifying specific fields being accessed during login and granting access to them, and checking for method access restrictions. Temporarily granting global read access to res.users can help diagnose if restricted access is the root cause. Also, verify module dependencies and review any custom code modifications to the login process. Grant the minimum necessary permissions to avoid security vulnerabilities and thoroughly test after any changes.

Hope it helps