I was adding a large number of deb's in a row. Aptly started to throw "too many open files**. Solution ulimit -n 64000 Reference https://github.com/aptly-dev/aptly/issues/351 aptly About the author Xuan Ngo is the founder of OpenWritings.net. He currently lives in Montreal, Canada. He loves to write about programming and open source subjects. View the discussion thread.