When user is ordering a catalog item it is stuck at checkout page.

When user is ordering a catalog item it is stuck at checkout page after clicking on submit and RITMs are not generated.

Check for the user if they have any "snc_read_only" role.

If a user has this role, they won't be able to insert any record and will you will see below errors in the logs.

Security restricted: access for table: sc_cart, user: <user_id>, operation: write -- from class: ReadOnlyRoleAccessHandler
DEBUG: Security restricted: access for table: sc_cart_item, user: <user_id>, operation: create -- from class: ReadOnlyRoleAccessHandler

When removing the role the user will be able to submit a catalog item without any issues.

You can also find more information in the docs below on snc_read_only role.

https://docs.servicenow.com/csh?topicname=c_ReadOnlyRole.html&version=latest