Troubleshooting

Make sure you are running the latest version of LMMS before troubleshooting issues. The latest version can be found at https://lmms.io/download.

General Troubleshooting

My settings won't save

Some users report that they can't save their settings. This is a recurring Windows issue, with reason not known in depth. To solve this problem, follow these steps:

• Close LMMS. Make sure nothing from LMMS is running in the background. You can look for this in your "Task Manager". (If you don't know how to use "Task Manager", restarting your PC is a good alternative.)

• In versions older than Windows 8, "Documents and Settings" is the folder you are looking for. In Windows 10, look in your "C:\Users\<Username>\. There is a file called .lmmsrc.xml.

• Use the search tool to find this file. .lmmsrc.xmlYou can't rename this file, but you can move it.

• Move it to one of the folders you have there, e.g. plugins. Now restart LMMS.

• You should be now asked to enter new settings, and these settings should be persistent.

• A terminal command version of this process exists:

  • Run CMD as administrator

  • Paste this command:

move %USERPROFILE%|.lmmsrc.xml %USERPROFILE%|.lmmsrc.xml.bak

LMMS is taking forever to load a project

Try adding exceptions in your antivirus for files the project depends on, such as:

• LMMS.exe

• RemoteVstPlugin.exe

• Plugins and their related data

Audio Troubleshooting

My Audio is Crackling

Buffer Size

Your buffer size may be too small, resulting in buffer underruns. To fix this, increase your buffer size. Note that this will increase latency.

Audio Interface

Certain audio interface configurations don't play nice with LMMS on some systems. If you are on macOS or Windows, make sure you have SDL selected. On Linux, if PulseAudio is producing these unwanted artifacts, try ALSA instead.

Track Volume

Your audio within LMMS may be too loud, resulting in digital clipping. This can be fixed by reducing the volume of the instruments in LMMS (either with the "VOL" knobs or through the mixer).

Volume Envelopes

If an instrument has attack or release values small enough, the rapid change in volume can sound like clicks or pops at the beginning or end of each note. Increasing the attack and release values for the culprit instrument's volume envelope can fix this kind of clicking. Ensure that the envelope amount (AMT) is set to full.

I Can't Hear Anything

Dummy

Certain audio interface configurations (specifically Dummy) just don't work. If you are on macOS or Windows, make sure you have SDL selected. Try to avoid PortAudio if possible.

JACK-transport

If you have JACK selected as your audio interface and you are experiencing no audio output, JACK-transport might not be running. Start an application like qjackctl and click on "play" or its equivalent. LMMS should automatically should start JACK-transport on startup, but this fails on some systems.

You may also need to connect LMMS to your sound card, using the patch bay in qjackctl.

The Audio Lags or is Delayed

Buffer Size

Buffer size is directly related to latency. If you can, try decreasing your buffer size to minimize latency.

My effects, especially echo or reverb, are not working smoothly.

Effects running without input

Go to Edit > Settings > General settings (Gear icon). There is a toggleable option "Keep effects running even without input". Make sure this option is enabled. If it is disabled, your echo and reverb will stop being active when they no longer detect an input audio, and this can cause them to cut off.

If you do not wish to enable this option for any reason (usage of certain very specific noisy plugins being a primary use case), turn up the "Decay" knob of the effect (located next to the "W/D" amount knob) displayed in the effect chain.

Video Troubleshooting

LMMS has very small windows

LINUX

Try using a shell script:

#!/bin/bash
export QT_AUTO_SCREEN_SCALE_FACTOR="0"
export QT_SCREEN_SCALE_FACTORS="eDP-1=2.5;HDMI-1=2.5;DP-0=2.5".<absolute path to lmms AppImage>

Set chmod +x <script name> and then make a symlink in a desired location.

You have to add all your connected monitors to QT_SCREEN_SCALE_FACTORS in order to make it work with all connected monitors.

Development Troubleshooting

LMMS Segfaults and There are No Error Messages on the Console

Use the GNU Debugger to run LMMS again, and try to replicate the crash:

$ gdb lmms
GNU gdb 6.X
Copyright (C) 2006 Free Software Foundation, Inc.
...

(gdb) r
Starting program: lmms
...

If a segfault happens, LMMS will freeze and you'll get some information on the terminal. Entering bt or bt full will show a backtrace you can report.

Make sure you have debugging symbols in LMMS. That usually means compiling with the -g flag and not stripping the symbols afterwards.

I Compiled LMMS With VST-Support, but it Doesn't Work at All

Make sure you didn't pass -fomit-frame-pointer in a FLAG-parameter to configure. This is known to lead to an unusable LVSL (LMMS VST Support Layer).