Problem: An application update may require the previous version's installation media. If the media is already removed from ccmcache, the installation might fail.
If the installation media was already removed from original source (ccmcache), MECM client can use a MECM distribution point as an alternative package source. MECM source management doesn't work if communication between distribution point and the client is secured. Make sure your distribution points communication is set to HTTP with Allow clients to connect anonymously enabled.