apt-cacher errors

[Adam Weremczuk <adamw@matrixscience.com>]

Hi all,

On 24th March (last Sunday) I received the following (for the first time):

Subject: Cron test -x /usr/share/apt-cacher/apt-cacher-cleanup.pl && /usr/share/apt-cacher/apt-cacher-cleanup.pl

Error: cannot open ../headers/debian_dists_wheezy_Release for locking: No such file or directory
Failed to open filehandles for debian_dists_wheezy_Release. Resolve this manually.
Exiting to prevent deletion of cache contents.

The above all came from systems originally running wheezy which were upgraded to stretch about 2 years ago.

Questions:

1. How to get rid of these errors? I would prefer to avoid spending half a day deciphering a chain of Perl scripts which I'm not familiar with.
2. What specifically happened last week to trigger this behavior? Was it e.g. a permanent removal of all wheezy repos and references?

Regards,
Adam