Chrome device debug logs
This article is for IT administrators managing Chrome devices.
If you experience problems with a managed Chrome device, you can troubleshoot using the Chrome device debug logs and Log Analyzer. Collect the logs, let the Log Analyzer tool examine them for you, and then review the results to resolve the problem. The logs are also useful if you need to contact support about a problem.
The logs are in the /var/log directory, and you can access them by typing file:///var/log in the browser address bar. You can use net-internals to export the contents of /var/log and all its sub directories into a zipped .tgz file.
To export the debug logs:
- On a managed Chrome device, browse to chrome://net-internals/#chromeos.
- (Optional) Select a debug mode. For example, if you're having Wi-Fi interruptions, select Wi-Fi. If you don't select a debug mode, net-internals will capture general device debug logs.
- Open a new tab and reproduce the issue.
- Go back to the net-internals tab and click Store Debug Logs.
- To access the logs, click and select Files.
For more information about net-internals, see Troubleshoot with net-internals.
Log Analyzer is a log-parser that examines device logs for managed Chrome devices.
To examine Chrome device debug logs with Log Analyzer:
- Go to Log Analyzer.
- Do one of the following:
- Paste the contents of the debug logs into the box.
- Upload the log file.
- From the log source drop-down list, select Chrome OS device log
- Click Analyze.
When the analysis is complete, Log Analyzer will show that there was nothing to report or display observations extracted from the logs along with explanations. In some cases, the observations may contain links where you can find more information.
Tip: The logs cover the life of a device so try to figure out when the issue happened to make searching the observations easier.
- If you see
ieee80211_reasoncodein the Log Analyzer output, check a third-party site, such as the Cisco® Support Community, for details on what these codes mean.
- Enrollment failures often put device management server request codes in the logs. For details on server error codes, see Device management errors.
You should only read the logs manually as a last resort. Use Log Analyzer first to troubleshoot a problem. If you decide to examine the device logs yourself, use the information below as a guide.
Debug log file structure
The hardware ID and model of the device is at the top of the file and looks like this:
Includes information about the boot process.
Shows system events such as when a device was turned on or off.
Includes messages to and from the kernel.
These logs are helpful for issues where devices aren't connecting to the right networks or aren't connecting at all and include:
Example of net.log
The following lines show the device has found an available 2.4 GHz and 5 GHz wireless network:
Later in the logs, there's additional information about the strength of the available connections, including the MAC address of the access point, frequency of the signal, noise and signal levels, and signal-to-noise ratio:
The logs list the available networks in order of preference, which is helpful if a device isn't connecting to the expected network.
A Chrome device attempts to select the best available network that meets a certain criteria. In this example, devices were connecting to a 2.4 GHz network instead of a 5 GHz network. The logs show that the Chrome device rated the 2.4 GHz network higher based on the signal-to-noise ratio (28/27 over 22/21), so it chose to connect to it instead.
Contains information about sandboxing.
Shows the sequence of events for checking on the date for updating the system.
These logs are useful for issues where devices won't update. They show information about communication between a device and omahaproxy for updates, including the response from the server.
This folder contains information about Chrome crashes, which can be difficult to decipher. See Troubleshoot Chrome crashes for more information. You can find crash report information by browsing to chrome://crashes. The most recent file in the /Chrome folder is named chrome, and older files are denoted with a timestamp.
Timestamp format: Timestamps have some high-level operating system and browser rendering messages.
Contains log metrics in a simple key=value format for easy parsing.
Contains information about actions performed by the power manager.
|file:///var/log/ui||Contains issue records about the user interface or graphics.|
|file:///var/log/update_engine||Chrome moves older update log files to this folder. The latest update log is named /update_engine.log.|
|file:///var/log/xorg||Contains hardware and system information.|