cnMatrix™ configuration may get corrupted after software upgrade via cnMaestro™
Document Number FSB9089
Revision v0001
Download the PDF version Application Global
Effective Date Aug 2, 2023
Expiry Date N/A
X Warranty Service   High – Perform immediately
  Informational X Medium – Perform at next scheduled maintenance
  Customer Specific   Low – Perform when system exhibits symptoms

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Subject: A cnMatrix switch running software version 4.6, 4.6.1, or 5.0 may experience corruption of the configuration when upgraded to a new software image via cnMaestro. This corruption can cause various symptoms, such as loss of connectivity to the switch.

Software/Configuration AFFECTED: Any cnMatrix switch running 4.6, 4.6.1, or 5.0


  1. This problem may present itself only when upgrading from software versions 4.6, 4.6.1, or 5.0 to a later SW version.
  2. Because of this problem, 4.6, 4.6.1, and 5.0 have been removed from the Cambium support site and cnMaestro.
  3. This problem happens only when upgrading via cnMaestro. The problem does not exhibit itself if the cnMatrix switch is upgraded via a CLI session or through a Web GUI session.
  4. This problem is intermittent.
  5. After the upgrade of a new image and post reboot of the switch, the configuration data could be corrupted. The new image will try to operate with this corrupted data leading to undesired operation which may require local access to the switch to recover.
  1. Cambium has made available a new software image 5.0.1 that solves this problem.
  2. Cambium strongly recommends that cnMatrix switches running software version 4.6, 4.6.1, or 5.0 be upgraded to 5.0.1.
  3. There are 3 ways to safely upgrade the cnMatrix switch to 5.0.1 without seeing the problem described in this FSB:
    a. Upgrade using Web GUI – Use HTTP, TFTP, SFTP, or SCP
    b. Upgrade using CLI – Use SFTP or TFTP
    c. Upgrade using cnMaestro:

    i. Disable Auto Reboot and upgrade image. This may be done once for all switches in the Switch Group. This operation is performed on the SW Update page. Under the ‘Switches’ tab, select all switches and then select the ‘Software Upgrade’ option from the ‘Actions’ button (right side of screen). Select 5.0.1 or later. Be sure to check the ‘Disable Auto Reboot’ box. Then start the upgrade by clicking the ‘Add Software Job to devices’ button.

    ii. Confirm that the SW upgrade has been completed by navigating to the ‘Administration’ icon on the main cnMastro page, then select the ‘Jobs’ option from the drop-down menu and select the ‘Software Update’ tab. Make sure the SW upgrade job is completed.

    iii. Next, write the configuration to non-volatile memory. This step can also be done once for all switches in the switch group. Go to the switch group ‘Configuration’ tab. Select the ‘User-Defined Overrides’ option. Then enter the following text: Be sure to click the ‘Save’ button. write startup-config end

    iv. Apply the configuration to the switches. Under the “Switches” tab, select all switches and then select the ‘Configuration’ option from the ‘Actions’ button (right side of screen). Select the switch group and then initiate the configuration push by hitting the ‘Apply Configuration’ button. – If this configuration sync causes an error, repeat this step.

    v. At this point you must remove the ‘User-Defined Overrides’ commands that you entered in step iii. Click the ‘Save’ button.

    vi. After you’ve confirmded that all switches are ‘In Sync’, wait 5 minutes to make sure configuration changes have been saved.

    vii. Reboot each switch in the switch group, one by one.

Once 5.0.1 or later is running on the switch(es), all future upgrades may be done as usual.

If you have questions or concerns, please contact Cambium Technical Support at the following:

For more details download the PDF version 

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