1. Introduction

Not so long ago I had the following issue:

The following packages have unmet dependencies.
libc6-dev : Breaks : libgcc-9-dev (< but 9.2.1-19 is to be installed

I was trying to install Blueman to be able to easily deal with my Bluetooth devices on Kali Linux, and then this error popped up.

2. Solution

2.1. Find the var/lib/dpkg/status file and open it with handy text editor

To solve this issue, we need to open the var/lib/dpkg/status file with one of the text editors and remove info related to libgcc-9-dev. For this purpose, we'll be using nano text editor:

sudo nano /var/lib/dpkg/status

You'll notice that the file consists of a list of package names and their statuses. Our goal here is to locate libgcc-9-dev package info block.

2.2. Locate the libgcc-9-dev package info in the file and remove it

So, look for the following block in the text:

Package: libgcc-9-dev
Status: install ok installed
Priority: important
Homepage: http://gcc.gnu.org/

When you find it, delete the whole block, from the Package to the Homepage line and after that save and close the file.

2.3. Update & Upgrade

After you removed the libgcc-9-dev block from the status file, do the system update&upgrade:

sudo apt-get update
sudo apt-get upgrade

2.4. Fix broken installations

Execute the following command to fix broken installations:

sudo apt --fix-broken install

3. Conclusion

In this short tutorial we showed how to solve libc6-dev : Breaks : libgcc-9-dev (< but 9.2.1-19 is to be installed issue.