What is a "Failed to load module "module-ladspa-sink"" error?

I found this blog post with the same error and an explanation:

A few days ago I started having issues with the equalizer that is, no sound. I removed the equalizer as well as ladspa-sdk. I promptly forgot about the whole thing until I rebooted and my machine began running super slow. Checking in syslog I found stuff like this:

pulseaudio[3662]: module-ladspa-sink.c: Failed to load LADSPA plugin: file not found
pulseaudio[3662]: module.c: Failed to load module “module-ladspa-sink” (argument: “sink_name=ladspa_output.mbeq_1197.mbeq master=alsa_output.pci-0000_05_00.0.analog-stereo plugin=mbeq_1197 label=mbeq control=-0.2,-0.2,-0.2,-0.2,3.5,3.5,3.5,3.5,3.5,3.5,3.5,2.5,2.5,0.0,0.0″): initialization failed.
pulseaudio[3662]: main.c: Module load failed.
Failed to initialize daemon.
pulseaudio[3660]: main.c: Daemon startup failed

Clearly the equalizer had left something behind when I removed it. Turned out the problem was in ~/.pulse/default.pa. The file had been modified in the install and not removed with it. The offending lines were at the end of the file. They looked like:

### Generated from: pulseaudio-equalizer
load-module module-ladspa-sink sink_name=ladspa_output.mbeq_1197.mbeq master=alsa_output.pci-0000_05_00.0.analog-stereo plugin=mbeq_1197 label=mbeq #control=-0.2,-0.2,-0.2,-0.2,3.5,3.5,3.5,3.5,3.5,3.5,3.5,2.5,2.5,0.0,0.0
set-default-sink ladspa_output.mbeq_1197.mbeq
set-sink-volume alsa_output.pci-0000_05_00.0.analog-stereo 65536
set-sink-mute alsa_output.pci-0000_05_00.0.analog-stereo 0
### END: Equalized audio configuration

I commented out all lines shown by adding a # at the beginning of each line and saved the file. Problem solved.

So in short:

sudo nano ~/.pulse/default.pa

scroll down to the line shown in the quote and add a # in front of all the lines. Save and exit.

In newer versions, this file could also be at ~/.config/pulse/default.pa.