Good news: you’re running Cyanogenmod, the most popular open source version of Android. Pure Android, no bloatware crapplets from the carrier or manufacturer, and better device performance and battery life.
Bad news: Cyanogenmod has a bug in the camera driver. This is a well known bug; if you Google “cyanogenmod camera bug” you will find lots of info on it. Occasionally the camera won’t work and you have to reboot the phone to get it working again. There is no real fix to this bug.
Good news: there is a simple workaround that fixes it in a few seconds, no reboot needed.
Android has a background process called mediaserver. It is always running and one of the many things it does is control access to the camera. This process has a bug in which it locks or hangs the camera driver, making the camera inaccessible.
This mediaserver process is part of Android and starts automatically during boot. The neat thing is, if mediaserver is ever killed, Android detects this and immediately starts a new instance. When this happens, it clears the camera lock and the camera works again.
So, to fix this problem all you have to do is kill the mediaserver process. Android is Linux, so you could simply open a terminal and run the command killall mediaserver. But it’s not quite that simple. Since mediaserver is a system process, you must have root privileges to kill it. Fortunately, that’s easy with Cyanogenmod.
Rooting Cyanogenmod is easy – root is already built in, you only need to enable it.
Go to Settings, About Tablet, and tap Build Number repeatedly. A toast will pop up saying, “X more presses to enable developer mode”. Keep tapping until Developer mode is enabled.
Hit back (to Settings) and you’ll see a new option: Developer options. Tap it. Scroll down to Root access, and enable it.
Reset in a Terminal
Now you can open a terminal and run the command su (to become root). A popup will appear asking whether grant root access to the terminal. Allow it – you’ll only have to do this the first time. Then (back at the terminal command prompt) run the command killall mediaserver. Alternately, you can do it all in a single command: su – c “killall mediaserver”. If the camera was stuck, it’s now working again. It only takes Android a couple of seconds to detect that mediaserver has been killed and restart it.
NOTE: if the terminal doesn’t have a killall command, install BusyBox. It installs a bunch of standard Linux command line tools, including killall and many others.
Reset the Easy Way
Opening a terminal and entering a couple of commands only takes a few seconds, but you might want an even quicker and easier way to reset the camera driver. How about an app that you simply touch, and it instantly kills mediaserver in the background? There are several versions of this app available if you google for them. I built one myself using Tasker. It runs standalone on any Cyanogenmod device – doesn’t need Tasker to run.
This app is an APK that you will be side loading. For security reasons, side loading is disabled by default in Cyanogenmod. To install this app (or any other APK) you need to go to Settings, Security, and enable Unknown Sources.
Now download this APK file and copy it to your device, for example in the “Downloads” folder. Just like you would for any other file like a JPG photo or MP3 song. Use the Cyanogenmod file manager to navigate to the Downloads folder and touch the APK file. This will install it.
After you’ve installed it, if you want to you can disable Unknown Sources. The app will continue working since it’s already installed.
The first time you run this app it will ask for root privileges (needed to kill the system mediaserver process). Grant them. It won’t ask again. When the app runs it will pop up a message saying “Camera Reset”, which will disappear in about 1 second.
NOTE: I built and shared this APK only to help Cyanogenmod users – it has no ads, no telemetry, no viruses, and is legal and free. However, it has no warranty. Know what you’re doing and don’t blame me if it doesn’t work, breaks your device, or makes your hair fall out. If you don’t trust me or this source, use a different app from somewhere else or write your own.