# Update Debian 10 (buster) to Debian 11 (bullseye)

### 1. Check version

```bash
cat /etc/os-release
PRETTY_NAME="Debian GNU/Linux 10 (buster)"
```

### 2. Update and upgrade

```bash
sudo apt update -y && sudo apt upgrade -y
```

### 3. Distro upgrade

```bash
sudo apt dist-upgrade
```

### 4. Update Package repos

Replace with sed distro name

```bash
sudo sed -i 's/buster/bullseye/g' /etc/apt/sources.list
```

Update debian-security lines in `/etc/apt/sources.list`

```bash
## Locate these:
deb http://security.debian.org/debian-security bullseye/updates main
deb-src http://security.debian.org/debian-security bullseye/updates main

## Replace with these:
deb https://deb.debian.org/debian-security bullseye-security main contrib
deb-src https://deb.debian.org/debian-security bullseye-security main contrib
```

Final list should look like this:

```bash
deb http://deb.debian.org/debian bullseye main
deb-src http://deb.debian.org/debian bullseye main
deb https://deb.debian.org/debian-security bullseye-security main contrib
deb-src https://deb.debian.org/debian-security bullseye-security main contrib
deb http://deb.debian.org/debian bullseye-updates main
deb-src http://deb.debian.org/debian bullseye-updates main
deb http://deb.debian.org/debian bullseye-backports main
deb-src http://deb.debian.org/debian bullseye-backports main
```

Update repos:

```bash
sudo apt update
```

### 5. Perform minimal system upgrade

```bash
sudo apt upgrade --without-new-pkgs
```

Press yes on prompt: 

### 6. Perform full upgrade to Deb11

```bash
sudo apt full-upgrade
```

Press `keep current version` 

### 7. reboot and check version

```bash
reboot
cat /etc/os-release
```