MID Servers can't be used after upgrading to Yokohama Patch 12 Hot Fix 1 - Known Error

MID Servers can't be used after upgrading to Yokohama Patch 12 Hot Fix 1 Description ServiceNow has identified an issue where MID servers could end up in an upgrade loop after the instance is upgraded to Yokohama Patch 12 Hot Fix 1. This occurs because after the instance upgrade, MID Servers automatically attempt to upgrade to match the instance version. However, due to an issue with the MID server build, an incorrect version "mid-core.02-09-2026_0235" is packaged in the MID Server Build which causes a version mismatch, resulting in a continuous upgrade loop.

IMPORTANT NOTE: You can IGNORE this KB completely if:

Your ServiceNow instance is NOT on 'Yokohama Patch 12 Hot Fix 1' version Your ServiceNow instance was upgraded on or after February 18th, 2026 You are AFFECTED by this issue and should follow the workaround steps if:

Your ServiceNow instance was upgraded to 'Yokohama Patch 12 Hot Fix 1' before the fix was applied Your MID servers are stuck in an upgrade loop If you have Pinned the MID server to 'yokohama-12-18-2024__patch12-01-20-2026_02-03-2026_1624' by adding a MID Server property (ecc_agent_property) - mid.pinned.version as mentioned in an earlier version of this KB/Workaround: you can delete this MID server property so that your MID servers can upgrade properly to the latest version. MID Server Forms will be showing a message that upgrade is recommended. This earlier applied workaround can be deleted now as the underlying build issue is resolved. Once the MID Server property (ecc_agent_property) - mid.pinned.version is deleted, MID servers will upgrade automatically.

Steps to Reproduce

It is not possible to reproduce this issue now, as ServiceNow has fixed the underlying build issue and the MID servers should be able to upgrade to Yokohama Patch 12 Hot Fix 1 version without any issues.

But when customer instances faced this issue earlier (before the fix), the MID servers were reporting incorrect version as below after upgrading to Yokohama Patch 12 Hot Fix 1.

The MID Server's Agent log will show the following, which will initiate another auto-upgrade. But it is going to replace the files with the same files, so this Loop will continue:

Installed: [mid-core.02-09-2026_0235.universal.universal.zip, mid-jre.yokohama-12-18-2024__patch6-hotfix1-08-01-2025_08-05-2025_2351.windows.x86-64.zip] Missing: [mid-core.yokohama-12-18-2024__patch12-hotfix1-02-06-2026_02-09-2026_2259.universal.universal.zip, mid-upgrade.yokohama-12-18-2024__patch12-hotfix1-02-06-2026_02-09-2026_2259.universal.universal.zip]

Workaround Important: ServiceNow has now fixed the underlying build issue. This workaround is only needed for MID servers that are currently stuck in an upgrade loop

For MID servers currently stuck in an upgrade loop: Navigate to MID Server -> Properties from the navigation menu (or go to ecc_agent_property table) Select the specific MID server that is experiencing the upgrade loop issue Search for the property name 'mid.pinned.version' Take action based on what you find: If 'mid.pinned.version' property already exists: Check the current value. If it's already set to '02-09-2026_0235', no action is required we can move to next step If it's set to a different value, do NOT modify it. This MID server was likely pinned for another legitimate reason and should remain as is. If 'mid.pinned.version' property does NOT exist and the MID server is stuck in an upgrade loop: Create a new MID Server property with name 'mid.pinned.version' and value '02-09-2026_0235' Wait for approximately 1 minutes to allow the MID server to stabilize with the pinned version Restart the MID server service After restart, verify that the MID server is stable and no longer attempting to upgrade The restart will clean up the affected downloaded packages from the agent folder After confirming MID server stability: Once you've confirmed the MID server is stable and showing as "Up" in the instance (no longer trying to upgrade):

Navigate back to MID Server -> Properties Select the MID server that was pinned to address this issue Find and delete the 'mid.pinned.version' property to unpin the MID server Click on "Upgrade MID" to trigger a controlled upgrade process The MID server should now successfully upgrade to the correct version Important Notes:

If you have multiple MID servers on the same instance, you must evaluate each one individually Only pin MID servers that are actually experiencing the upgrade loop issue Do not modify MID servers that were pinned for other legitimate reasons MID servers that were already pinned to '02-09-2026_0235' specifically for this issue can follow the unpinning process once they are stable