amixer: Unable to find simple control 'Master',0

This happens if the control name Master doesn't exist on your system. This control name is just the default setting in i3-volume as it is the most common name found on most systems. Use the command amixer scontrols to find your correct mixer control. The name is within single quotations. Once you have the name, you can set it with the -m option of the volume script.

Example settings for i3wm configuration if the your mixer control name was "Speaker" instead of "Master":

# Review the lines below and append to ~/.config/i3/config

## Volume control

# Path to volume control, without trailing slash
set $volumepath ~/i3-volume

# Command for the status line
#   ie: i3blocks, i3status
set $statuscmd i3status

# Signal used to update the status line
#   i3blocks uses SIGRTMIN+10 by default
#   i3status uses SIGUSR1 by default
set $statussig SIGUSR1

# Amount to increase/decrease volume as a percentage
set $volumestep 5

# alsa-utils settings
#
# To configure a default card, see https://www.alsa-project.org/main/index.php/Asoundrc
#
# Card number to control.
#   If not specified, i3-volume will let `amixer` use a default.
#   List cards: aplay -l
#set $alsacard 1

# Mixer control name
set $alsamixer Speaker

bindsym XF86AudioRaiseVolume exec --no-startup-id $volumepath/volume -an -t $statuscmd -u $statussig -m $alsamixer up $volumestep
bindsym XF86AudioLowerVolume exec --no-startup-id $volumepath/volume -an -t $statuscmd -u $statussig -m $alsamixer down $volumestep
bindsym XF86AudioMute        exec --no-startup-id $volumepath/volume -an -t $statuscmd -u $statussig -m $alsamixer mute

hastinbe / i3-volume

amixer: Unable to find simple control 'Master',0 #37