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Synaptic errors

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Here are some common error messages encountered in using Synaptic (or apt-get):

GPG errors

  • Messsage: public key not available
  • Problem: you do not have a correct key installed
  • Solution: click Start menu > MX Tools > Check Apt GPG.

NOTE: see also BADSIG below

Package authentication

  • Message: Packages could not be authenticated
  • Explanation: Many repositories, including all of Debian’s repositories & MX repositories, use a GPG key to verify that you are connected to the real repository instead of having been rerouted by a highjacked DNS or a man-in-the-middle attack to a fake site. This is a very slight possibility, but for production machines the extra security is worth the check. The MEPIS Community Repositories don’t use such a key at this time, although new CR packages are gpg-signed by the packagers.
  • Solution: If this error occurs when installing packages from the Community Repository it is safely ignored. If it occurs with packages from the Debian repositories, do not continue the installation and report the error.

No header, problem with merge list

  • Message: Encountered a section with no Package: header. Problem with MergeList etc.
  • Problem: Files have been corrupted for some reason.
  • Solution: There are two main variants of this problem.

Variant 1. If the error message includes a reference to /var/lib/dpkg/status, open a terminal and type:

su -c "cp var/lib/dpkg/status-old var/lib/dpkg/status"
su -c "apt-get update"

Variant 2. If the error message references a file in /var/lib/apt/lists, open a terminal and type:

su -c "find /var/lib/apt/lists/* -type f | xargs rm -f"
su -c "apt-get update"

Other files than these may be referenced in the error message. They can be fixed by editing the file which is producing errors manually. Open the file as root and look for these entries (there should be 3):




If you remove those the MergeList file should be correct again.

Broken package

  • Message: you have a broken package and are told to use the Broken filter to find it
  • Problem: you tried to install a package that had unmet dependencies
  • Solution: click on Status in the lower left corner of the Synaptic screen, then on the entry “Broken package.” Click on the package and remove it. Reload the repos.

Cache limit exceeded

Message: Dynamic MMap ran out of room. Please increase the size of APT::Cache-Limit. Current value: 20000000.
Problem: Cache-Limit is too small to handle new package cache
Solution: Click Start Menu > System > Root Terminal, and provide root’s password. Open


Change line from

APT::Cache-Limit 20000000


APT::Cache-Limit 70000000 

If you have a large cache already, then run apt-get clean.

NOTE: you may get this error if you are trying to add the repos of a more recent version of Mepis or Debian. In that case, open “Dolphin as su” and click the /etc/apt/sources.list file. Delete any repos that do not belong, using Repos – MX 14 or Repos MX – 15 as a guide.


  • Message: similar to “GPG error: <url and name of mirror> The following signatures were invalid: BADSIG E6AD81A8B9FBE3CE <name of maintainer and contact info>”
  • Problem: The GPG signature of the repo has expired
  • Solution: maintnainer has to be notified

DNS problems

  • Message: “Something wicked happened resolving…”
  • Problem: apt is unable to resolve the DNS names
  • Solution: Wait a few minutes, then try again. If problems persist, consider moving to OpenDNS

v. 20150624

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