How to fix E: The update command takes no arguments in APT

The simplest fix is to remove any arguments from the apt update command:

# WRONG - produces the error
apt update python3
apt-get update /etc/apt/sources.list

# CORRECT - apt update takes no arguments
sudo apt update
sudo apt-get update

The command will refresh all configured package sources and update your local package cache.

If you need to update and then install packages, use two separate commands with proper chaining:

# WRONG - mixes update with install
sudo apt update python3

# CORRECT - use && to chain commands properly
sudo apt update && sudo apt install python3

# Or run them separately
sudo apt update
sudo apt install python3

The && operator ensures the second command only runs if the first succeeds. Never use other special characters like $$ instead of &&.

If you're using apt update in a shell script, ensure proper escaping and shebang:

#!/bin/bash
# Ensure shebang is present at the very top

# Properly quote arguments if any
apt update

# Chain multiple apt commands correctly
apt update && apt upgrade -y && apt install -y package-name

Common script issues:
- Missing #!/bin/bash shebang at the start
- Incorrectly escaped quotes in command chains
- Mixing tabs and spaces (YAML files especially)
- Hidden characters from copy-paste

After running apt update correctly, verify your package sources are configured:

# List all configured sources
cat /etc/apt/sources.list

# List sources in separate files
ls /etc/apt/sources.list.d/

# Check for syntax errors in sources
apt-get check

If you see network errors or missing sources, you may need to:
- Add Ubuntu universe/multiverse repos: sudo apt-add-repository universe
- Update your sources.list file if it's misconfigured