I spent quite a while searching for solutions to this issue:

Reading Package Lists... Error!

E: Dynamic MMap ran out of room

I found several posts and sites that mention updating the cache limit, but that did not work. Here’s what I found though.

First, create the file if it does not exist.
/etc/apt/apt.conf

Then, add this:

APT::Default-Release "stable"; 

APT::Cache-Limit "141943904";

And that did the trick!  You can probably find this lots of places, but it took me too long to find the right fix, so I saved this here for myself!

Have a great day!