Problem
The below error message comes up on a computer attached to an Epson scanner (frequently a model DS-530):
Known Issue
This is a known issue that happens for an indeterminate reason on the Epson DS-530 scanners (commonly in the Health Center). The scanner will not operate, insisting that "The scanner is in use or unavailable. Please wait." Assuming that no amount of waiting or rebooting resolves the issue, the below fix can be applied.
Resolution
The first step to resolving this issue is to remove all of the existing Epson scanner programs from the laptop.
- Go into Settings, Apps, Installed Apps
- Search for Epson at the top
- Remove all installed components.
- After all of the uninstalls are complete, restart the computer.
After restart, you should download a clean installer of the scanner drivers directly from Epson's support website.
- Install the drivers normally, making sure to uncheck the EMC ISIS drivers, as they are known to cause problems.
Once the installation is complete and the scanner is detected, it should prompt to update the drivers and applications automatically. If the prompt doesn't come up, it can be launched from the start menu: "Epson Software Updater".
It is recommended that only the drivers are updated; application updates are not needed at this time, but can be applied if there are further issues. 
Once this is complete, the scanner should be working again.