JSI Tip 2828. 'All Pipe Instances Are Busy' error when copying a file to a LPT port?

When you copy a text document to a LPT port (COPY <Drive:>\Folder\FileName.TXT LPT1:), you may receive an error:

All pipe instances are busy.

If you close the CMD prompt and re-open one, the COPY generates the same error.

This problem will occur if the COPY command was issued at the same time that the spooler starts to print a spooled print job.

To fix the problem:

net stop spooler
net start spooler