USB printers stopped working after 25H2. Where should I start?

First check whether this affects one printer model or several, and note the exact models and driver versions. If the issue is limited to a particular driver, remove its software and install a current version from the manufacturer. For compatible printers, testing a universal driver can help narrow down whether the vendor driver is the cause.

Look at the spooler failure in Event Viewer and identify the error or module involved rather than relying only on the repeated start-failure message. If that does not point to a cause, a process monitor trace during startup may show which file, registry entry, or permission is making the service exit. I would avoid changing the service account unless the logs suggest an account or access problem.

Before changing anything broad, try one affected machine with the printer software removed, then reinstall a current driver and reconnect the printer. If you have multiple printer types, test each separately. That helps distinguish a particular driver problem from something affecting the spooler across the system.

If this is happening across several machines, pause further rollout while you compare the affected systems and gather the spooler event details. A staged test before deploying major updates widely can limit disruption, especially for label or receipt printing that depends on specific drivers.