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Many people have reported running into the UniFi Controller Startup Failed issue. Some users encountered the issue while trying to update the UniFi controller software, while others received the error after launching the software for a few minutes. So far, many Windows 10 users have reported the UniFi controller failed to start error.


It fails with the error:

"Port 8080 is already in use by another program"

or sometimes

"Server takes too long to start... Failed to start."

What is the cause of the error? After going through many user reports, we have found several possible reasons why the UniFi controller won't boot up.

  • Lack of free disk space on the host system.
  • Incompatible or outdated JAVA installation.
  • There are special characters in the Windows profile username.
  • The required ports are not available for the UniFi Controller.
  • Database corruption.
  • Corrupted UniFi protocols.
  • Temporary errors in the UniFi controller software.

The above causes are used to identify the appropriate solutions. Now we will see how to fix the UniFi controller boot failure.

Empty space on the system hard drive


The Unified Controller software requires additional free space on the system drive to fully function. This error can occur if you do not have enough free space on your system hard drive. In this context, creating free space on your hard drive can fix the problem. To illustrate this, we will discuss the procedure for Windows.

  • Free space on drive C (system drive).
  • Then run the control application if it works correctly.

Change the engine specified in the system properties file

If the database was created by the storage engine "mmapv1", but the storage engine specified was "wiredTiger", this error can occur. In this context, forcing the control application to use the mmapv1 storage engine may fix the problem. As an illustration, we will discuss the procedure for a Windows computer.

  • Launch the file explorer and navigate to the driver application installation directory. This is usually the case:% USERPROFILE% Ubiquiti UniFi data
  • Now open the System.Properties file with notepad and add the following line to the end of: db.extraargs = --storageEngine = -mmapv1
  • Save your changes and exit Notepad.
  • Then launch the control application and check if it works properly.

Check if the required ports are not available

The ports required by UniFi are used by other programs. Change the ports according to the steps below.

  1. go to /logs/server.log
  2. There is a high probability that an equivalent ERROR will occur: address already used: JVM_Binding
    to (native method)
    EITHER :
    startup program ERROR: port 8080 is used by other programs
  3. Modify the ports used by the UniFi Network Controller.

Java incompatibility


At this time, Java 9 does not support the UniFi Network Controller. Use Java 8. The driver software release notes, which can be found with the software on our download page, contain release notes and requirements for each release.

Make sure that the correct version of Java is installed on your computer (64-bit). As of version 5.10.12 of the UniFi Network Controller, you need to use x64-Java as we only support the 64-bit WebRTC library. Uninstall Java, if applicable, and install Java 8.

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