Silent error when creating a guide with invalid characters

When creating a new repair guide for an unlisted device and entering in invalid characters in the device name (like "/"), the save button remains active but nothing happens and no explicit error is raised for the user.

The only way to notice this error is to hover over the question mark icon next to the invalid field, which is far from user-friendly.

Would there be a way to improve form validation and user feedback during guide creation steps?