[GLLUG] How to clear the Debian apt data without breaking the installed system?

[Chris Bell]

Hello,
I have Debian Stretch (testing) installed on a box which complains that the 
hash sums for some index files on a local mirror are incorrect, so it is 
unable to re-build the list for that mirror. The filenames do not exist, the 
index files supplied are compressed, and the compressed files are there, 
exactly the same as the official mirror sites, but the complaint does not go 
away. I can deselect the mirror in the /etc/apt/sources.list and do an update, 
then reselect it, and the complaints return. Can I safely delete a cache on 
disc without breaking the entire installation? Thanks for any advice.
Chris Bell