Problem

Packet Tracer fails to install with:

Dependency is not satisfiable: libgl1-mesa-glx 

Quick Fix

1. Download dependency packages
   Grab the .deb files listed here:
   https://github.com/PetrusNoleto/Error-in-install-cisco-packet-tracer-in-ubuntu-23.10-unmet-dependencies/releases/tag/CiscoPacketTracerFixUnmetDependenciesUbuntu23.10

2. Install gdebi

   sudo apt install gdebi 

3. Install dependencies

   cd ~/Downloads sudo gdebi ./libegl1-mesa_23.0.4-0ubuntu1.22.04.1_amd64.deb sudo gdebi ./libgl1-mesa-glx_23.0.4-0ubuntu1.22.04.1_amd64.deb 

4. Install Packet Tracer

   sudo gdebi ./Packet_Tracer821_amd64_signed.deb 

Credits

Original reference from PetrusNoleto (GitHub).