Debugging i3: How To

1. Verify you are using i3 ≥ 4.10

Only the latest major version of i3 is supported. To verify which version you are running, use:

$ i3 --moreversion 2>&- || i3 --version
Binary i3 version:  4.7 (2013-12-22, branch "tags/4.7")
Running i3 version: 4.7-84-gac74a63 (2014-01-01, branch "next") (pid 1995)

Your version can look like this:

4.7 (release version): You are using a release version. In many cases, bugs are already fixed in the development version of i3. Even if the bug is not a known fixed one, we will still ask you to reproduce your error with the most recent development version of i3. Therefore, please upgrade to a development version if you can.
4.7-85-g9c15b95 (development version): Your version is 85 commits newer than 4.7, and the git revision of your version is 9c15b95. Go to https://github.com/i3/i3/commits/next and see if the most recent commit starts with the same revision. If so, you are using the latest version.

Development versions of i3 have logging enabled by default and are compiled with debug symbols.

2. Enabling logging

If you are using a development version (see previous section), you don’t need to do anything — skip to section 3.

If you are using a release version with a custom ~/.xsession (or xinitrc) file, execute i3 with a line like this:

# Use 25 MiB of RAM for debug logs
exec i3 --shmlog-size=26214400

If you are NOT using an ~/.xsession file but you just chose "i3" from the list of sessions in your desktop manager (gdm, lxdm, …), edit /usr/share/xsessions/i3.desktop and replace the Exec=i3 line with:

Exec=i3 --shmlog-size=26214400

If you cannot restart i3 for some reason, you can enable debug logging on the fly:

i3-msg 'debuglog on; shmlog on; reload'

3. Reproducing the problem

Before submitting an issue, please make sure to close down on the problem as much as you can yourself. Here are some steps you should consider:

Find a deterministic, reliable way to reproduce the problem and provide it with your bug report.
Try using the default i3 config to reproduce the problem. If the issue does not appear with the default config, gradually adapt it to track down what change(s) to the config introduce the problem.
Reproduce the problem with a minimal setup, i.e., only use as few applications, windows and steps as necessary.
In addition, try to stick to applications that are common and, even more importantly, free / open source.
Before obtaining the log file, restart i3 in-place, execute the steps to reproduce the problem and then save the logs. This keeps the log file as small as possible and necessary.

Please be aware that we cannot support compatibility issues with closed-source software, as digging into compatibility problems without having access to the source code is too time-consuming. Additionally, experience has shown that often, the software in question is responsible for the issue. Please raise an issue with the software in question, not i3.

4. Obtaining the debug logfile

Caution

Logs may contain sensitive information, so please inspect the log before submitting it. Logs may be viewed by anyone, once posted. If you choose to redact the log, make an effort not to discard information which may be relevant to the issue you are reporting.

The beue you are reporting.

The beue you are