Cannot upgrade SwOS
Applies To
- CSS106 series (SwOS-only)
- CSS326 series (SwOS-only)
- CSS610 series (SwOS Lite-only)
- CRS3xx series (dual-boot: SwOS / RouterOS)
- CSS326-24G-2S+ (dual-boot: SwOS / RouterOS)
Overview
MikroTik switches that support SwOS store two separate firmware images in flash memory: a primary (active) image and a backup image. Under normal operation, the device boots from the primary image. When a firmware upgrade is initiated — either automatically via the web interface or manually via file upload — the device writes the new image to the primary slot and reboots into it.
Upgrade failures typically occur due to one of the following:
- Incorrect firmware file selected (wrong model or firmware branch)
- Interrupted write operation leaving the primary image corrupted
- Network connectivity issue preventing the automatic download from reaching MikroTik servers
- On dual-boot devices: device-mode policy restricting OS transitions (RouterOS 7.17+)
SwOS-only devices and dual-boot devices require different recovery procedures, described separately below.
Before You Begin
Warning: The reset button procedure described in this article will erase the active configuration and load factory defaults. Export a configuration backup from the System tab before proceeding.
Confirm which firmware file you need before attempting a manual upgrade. Each switch series uses a dedicated firmware binary — cross-series firmware files are not interchangeable and will be rejected or cause a boot failure. The correct file for your device can be found at:
Resolution
SwOS-only Devices (CSS106, CSS326, CSS610)
These devices do not run RouterOS and have no serial console boot menu. Recovery relies on the hardware backup firmware stored in a protected flash partition.
Step 1 — Attempt manual firmware upload
Navigate to the Upgrade tab in the SwOS web interface, select the correct .swos firmware file for your device model, and click Upgrade. Do not interrupt power during the write process. After the upload completes, the device will reboot automatically. Reload the web interface and verify the firmware version shown in the System tab.
Step 2 — Boot into backup firmware via hardware reset
If the manual upload fails or the device becomes unreachable after the upgrade attempt, the backup (primary) firmware can be force-loaded using the reset button:
- Disconnect power from the device.
- Hold the Reset button and reapply power.
- Continue holding the button for approximately 5 seconds until the device completes its boot sequence.
- Release the button.
The device will load the backup firmware and apply the factory default configuration. It will be accessible at 192.168.88.1 or at a DHCP-assigned address.
Step 3 — Reattempt manual firmware upload
Once the device is accessible on the backup firmware, repeat the manual upgrade procedure from Step 1. The backup firmware environment provides a clean state from which the upgrade is more likely to succeed.
Dual-Boot Devices (CRS3xx, CSS326-24G-2S+)
Dual-boot devices store both SwOS and RouterOS and can boot into either operating system. This provides additional recovery paths, including upgrade via the RouterOS CLI.
Step 1 — Attempt manual firmware upload
As with SwOS-only devices, first attempt a manual upgrade via the Upgrade tab in the SwOS web interface using the correct firmware file for your device.
Step 2 — Boot into backup SwOS via serial console
If the manual upload fails, connect to the device using a serial console cable with the following parameters:
| Parameter | Value |
|---|---|
| Baud rate | 115200 |
| Data bits | 8 |
| Stop bits | 1 |
| Parity | None |
| Flow control | None |
At the boot menu prompt, select:
p - boot primary SwOS
This loads the factory backup SwOS image. Once the device is accessible, reattempt the manual firmware upload as described in Step 1.
For further detail on the boot menu, see: Reset and Reinstall
Step 3 — Boot into RouterOS via reset button (no console access)
If no serial console port is available or no cable is at hand, the device can be forced into RouterOS using the reset button:
- With the device powered on, press and hold the Reset button.
- Hold until the user LED begins to flash (approximately 5 seconds).
- Release the button.
The device will reset the RouterOS configuration to factory defaults and boot into RouterOS.
Warning: This procedure resets the RouterOS configuration. Ensure a RouterOS configuration backup exists before proceeding if the device was previously running RouterOS.
Step 4 — Upgrade SwOS from RouterOS CLI
Once booted into RouterOS, SwOS can be upgraded directly without using the web interface. The following command fetches and installs the latest available SwOS firmware for the device:
/system swos upgrade
Internet access is required for this command to resolve and download the correct firmware package from MikroTik's update servers. Verify connectivity before executing.
For full documentation on managing SwOS from RouterOS, see: Configuring SwOS using RouterOS
Step 5 — Device-mode restriction (RouterOS 7.17 and later)
Starting with RouterOS v7.17, the device-mode policy restricts OS transitions between SwOS and RouterOS on dual-boot hardware. If the upgrade command fails or OS switching is blocked, explicitly permit the transition with:
/system/device-mode/update routerboard=yes
This command must be executed in RouterOS before re-attempting the SwOS upgrade or switching back to SwOS.
Step 6 — Return to SwOS
After the SwOS firmware has been successfully updated from RouterOS, set the default boot target back to SwOS and reboot the device:
/system routerboard settings set boot-os=swos
/system reboot
The device will restart and load the newly installed SwOS firmware.