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UniFi - Troubleshooting Offline Cloud Key and Other Stability Issues

This article will explain how to troubleshoot, resolve and prevent UniFi Cloud Key failures and stability issues.

Note: Before troubleshooting the stability issues, make sure to update your UniFi Cloud Key to the latest Official UniFi OS Console and UniFi Network application versions.


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All of the following symptoms can indicate stability issues with your Cloud Key:

  1. Flashing white LED indicating the UniFi Cloud Key is disconnected.
  2. Cloud Key may show as Offline in UniFi Remote Access Portal (
  3. The Cloud Key management UI may not be accessible via direct URL when typing the Cloud Key's IP on browser: https://[cloudkeyip]:8443/manage/
  4. UniFi service shows as not running through the web application (https://, Select option Configure > Maintenance > Service > Stop UniFi will be grayed out indicating it is already offline)
  5. UniFi service will not start by clicking the button "Start UniFi".


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1. Reboot

As a first step, some Cloud Key issues can be resolved with a simple reboot. If you have not done this, do so now. This can be done by following these steps: 

  1. Open the Cloud Key management portal in a browser by typing the IP address of the Cloud Key as URL: i.e.
  2. You may receive a Privacy Error. Click continue.
    • In Chrome, click Advanced > "Proceed to [IP of Cloud Key](unsafe)"
  3. Select Manage Cloud Key.
  4. Log in with UniFi Cloud Key credentials used at setup (username will be root). See our Related Articles below for credential questions. Open Settings > Hardware > and click on Reboot.

If this does not resolve the issue, then proceed to the next resolution. 

2. Reset Cloud Key

Nearly every UniFi Cloud Key failure, can be quickly resolved by a simple Reset and Restore of a backup file. The Cloud Key has made it easy to maintain backups in case of any failures. Auto Backup, if enabled, will create periodic snapshots that can be restored to in the case of any failures.

These are stored on the SD card and even if the Cloud Key is unable to be accessed manually, a reset of the device will permit a restore of the Auto Backup files on the SD card. Auto Backup is configured in the Network application under Settings > Auto Backup.

To ensure that you have enough intermittent backups should anything happen, it's recommended to have automated Weekly backups.

Follow the steps below to reset the Cloud Key:

ATTENTION: Resetting a Cloud Key wipes out everything that is not on the (optional) SD card: all data and settings. Prior to resetting your Cloud Key make sure you have backups available to restore from saved somewhere other than the Cloud Key. To be safe, make sure to download backups from Cloud Key through the Network application or via SSH prior to resetting and to verify which type of Data Retention you selected. Settings Only will only restore application settings and adopted devices. If using Cloud Key Gen2 Plus, Protect backups will only restore settings but all recordings will be lost. If no backup file is available, all settings and devices will need to be reconfigured and historical data will be lost.

 Reset Method 1: On the web browser

  1. Open the Cloud Key management portal in the browser by typing the IP address of the Cloud Key as a URL: i.e.
  2. You may receive a Privacy Error, in Chrome, click Advanced > Proceed to [IP of Cloud Key](unsafe).
  3. Click Manage Cloud Key on the right side.
  4. Log in with UniFi Cloud Key credentials used at setup. See the Related articles section below for credential questions.
  5. Select the Settings tab.
  6. Open the hardware tab by clicking the + sign.
  7. Click Factory Reset.


If access to the Cloud Key's management portal is not possible, use one of the following alternatives:

Reset Method 2: Hardware Button

  1. The reset button is at one end of the Cloud Key. See each model's Quick Start Guide for the exact location.
  2. Insert a paper clip or similar object into the small hole until the button depresses.
  3. Hold for five seconds, then release.
  4. The LEDs should indicate the Cloud Key is restarting and being reset to default state.
  5. Once completed, the Cloud Key should show a steady white LED if this was done properly.

Reset Method 3: SSH

  1. Use an SSH client like Putty (Windows) or Terminal (macOS).
  2. Connect to the IP address of the Cloud Key.
  3. Authenticate using SSH credentials as previously configured. See this article for help on Cloud Key password disambiguation.
  4. Once you log in successfully, enter the following command then hit enter:
    • ubnt-systool reset2defaults
  5. The Cloud Key will then reset to default. 

How to Restore from Last Working Backup

Once your reset has completed successfully your Cloud Key should be in a factory default state, which will eliminate any database corruption/corrupted configuration of the Cloud Key. Now you are ready to restore from your last known working backup. Here are instructions on how to restore from a backup:

Restore Method 1: Via UniFi Setup Wizard

  1. Open the Cloud Key management portal in the browser by typing the IP address of the Cloud Key as a URL: i.e.
  2. You may receive a Privacy Error, in Chrome, click Advanced > Proceed to [IP of Cloud Key](unsafe).
  3. Select Unifi Network Launch.
  4. The UniFi Setup Wizard will present you with a couple of options setup from scratch or restore from backup. In this case, we will select restore from backup.
  5. Select which backup option you want. This could be a backup from the Micro SD card (My local backups) or a backup file you have stored on your PC (upload backup file) then just select the file and click Restore.


Restore Method 2: On the web browser

  1. Open the Cloud Key management portal in the browser by typing the IP address of the Cloud Key as a URL: i.e.
  2. You may receive a Privacy Error, in Chrome, click Advanced > Proceed to [IP of Cloud Key](unsafe).
  3. Click Manage Cloud Key.
  4. Login with default UniFi credentials (can be a combination of either one of these, depending on production date): 
    • Username: ubnt
    • Password: ubnt
    • Username: root
    • Password: ubnt
  5. Go to the Controllers tab.
  6. Click the Stop UniFi button, once the Start Up Network button appears clickable and you opened the drop down menu "settings and maintenance for the UniFi Network controller" proceed to the next step.
  7. Click on Restore and you will get a menu of the available backups that you have on your Micro SD card.selectbackup.png
    This method will not allow you to restore from a file on your computer it will only work if you have auto-updates enabled with a Micro SD card inserted in the Cloud Key prior to doing the restore process. If those requirements are not met then you will need to use "Restore Method 1: Via UniFi Setup Wizard".

Potential Causes and Prevention

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Since Cloud Key Gen1 was released, a number of features have been added and improved via firmware to improve stability and prevent common issues. Because of this, it is always recommended that you upgrade your Cloud Key firmware to the most recent stable version, especially if you repeatedly encounter any stability issues.

If Cloud Key stability issues are not resolved with a reset/restore, or repeatedly come back, it is particularly important to identify and resolve the root cause. The majority of such reported issues are found to be a result of one of the following causes:

Cause 1: Power Outages/Interruptions

User Tip:This cause is associated with Cloud Key Gen1. The Gen2 model has a "graceful shutdown" feature that should prevent sudden power interruptions.

The Cloud Key stores data and Network application configuration in a MongoDB database. Even in small environments, there are ongoing database functions being performed at any given moment. If these database operations are interrupted as a result of a sudden power interruption, this can cause database corruption which will ultimately hinder the proper function of the Cloud Key. In some cases, after a power outage, the Cloud Key may be unable to start the UniFi service properly due to database errors resulting from the interruption.

If you find your Cloud Key is losing power frequently despite no power loss, you may also have a bad Ethernet Cable being used to power the device via PoE- replace the cable to resolve this.


  • Stability issues arise after a known power outage/interrupted power.
  • Persistent Cloud Key stability issues; testing with different ethernet cable fails to reproduce.

How to Prevent

  1. Power the UniFi Switch or other PoE supplying device up to a power source with battery backup to ensure that power remains uninterrupted in short power outages.
  2. Plug a small charged battery like those used for charging mobile phones into the Cloud Key via the micro USB port. This will prevent the Cloud Key from being shut off in a power outage from interrupted PoE.
  3. Replace faulty Ethernet cable with new cable if the Cloud Key loses power in cases where there is no power outage.
  4. Shutdown/Reboot Cloud Key gracefully using the button in UI rather than unplugging/plugging back in. 

Cause 2: Disk Space

The Cloud Key was built for compact form, ease of install and affordability. With this comes less disk storage than you’d find on a server that would otherwise be running the Network application. In most environments, this will not become an issue and requires little consideration. However, in larger environments or configurations that have opted to retain more detailed data and a larger number of backups, disk space can become an issue. For this reason, it is good to monitor the disk usage on the Cloud Key regularly just to ensure that the disk space isn’t over-utilized.



  • Storage Space Shows as close to 100% utilized
  • Cloud Key will shut down the application service without warning as disk space is exhausted/MongoDB is unable to write to the database further

How to Prevent

  • Periodically check the Cloud Key disk utilization through the WebUI > Configure > Main.
  • Limit the number of backups stored on the Cloud Key. If longer retention of backups/data is needed, download these files then remove them from Cloud Key storage.
  • Decrease the length of data retention in the Network application under Settings > Maintenance > Data Retention.
  • Perform regular compacts on Database under Settings > Maintenance > Compact Database.
  • Remove excessive backups under Settings > Auto Backup

Cause 3: Maximum Database Limit

All UniFi OS Consoles operate with the use of a MongoDB database. What’s unique about the Cloud Key Gen1 over most other consoles is that it has an ARMv7 32-bit CPU, and as such can only run 32-bit MongoDB. 32-bit MongoDB instances have a limitation over 64-bit mongo instances in that they can only support database sizes of approximately 2GB. See more info here.

As the complexity and scale of the UniFi management increases, the database will grow in size. As the Cloud Key Gen1 is geared towards smaller sites and portability/compactness, in most cases this will not ever be anything to worry about. However, given the 32-bit limit on size on the Cloud Key Gen1, if used in the largest environments (more than a couple dozen APs/UniFi devices), this limit will quickly be reached and prevent healthy function.

If you are unsure of whether your Network application should be using a Cloud Key or not, review the following guidelines: UniFi - Cloud Key's Device Management Limit


  • server.log indicates error identical or similar to the following:
    • <inform_stat-10> ERROR dev - Error in DeviceManager.processStat() com.mongodb.WriteConcernException: { "serverUsed" : "" , "err" : "can't map file memory - mongo requires 64 bit build for larger datasets"`
  • The database is close to 2 GB in size
  • Restoring from a backup may work until the limit is reached again.

How to Prevent

  • Make sure your UniFi deployment is not too large for the UniFi Cloud Key to handle. See here.
  • If the scale of the UniFi deployment on Cloud Key is growing too large, consider migrating to a software install of the Network application on a server with a 64-bit OS.
  • Verify the size of your backups is not approaching the 2GB limit users under Settings > Auto Backup.
  • Reduce Data Retention Settings, then Compact Database under Settings > Maintenance > Compact Database.

Other Causes

If you encounter an issue not covered by one of the above scenarios, get help on our Community. This article will continue to grow thanks to user feedback. 

However, if you still don't find a solution you may be dealing with hardware issues. These are very rare but can be encountered. In such cases, usually, the Cloud Key will fail to power on or the Micro SD card will not permit additional data to be written to the Cloud Key. If the issue is apparently a hardware issue and your device is under warranty, fill out the RMA form on to arrange a replacement.

Related Articles

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UniFi - Accounts and Passwords for Ubiquiti, UniFi OS and UniFi Devices

UniFi SDN - Repairing Database Issues on the UniFi Network Application

UniFi - How to Manage & Upgrade your Cloud Key

UniFi - How to Manually Change the Cloud Key's application version via SSH

UniFi - Supported PoE Protocols

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