vMotion failure - Received invalid swap bitmap lengths
Article ID: 442717
Updated On:
Products
Issue/Introduction
When attempting to perform a vMotion migration of a virtual machine, the task fails at the final stage (typically during the resume process on the destination host) with the following error messages:
- vCenter UI/Task Console:
Failed to resume destination VM: Bad parameter. - vmkernel.log:
####-##-##T##:##:##.###Z Wa(180) vmkwarning: cpu##:########)WARNING: Migrate: 7074: 5352231587107175880 S: Migration considered a failure by the VMX. It is most likely a timeout, but check the VMX log for the true error. - vmware.log:
####-##-##T##:##:##.###Z In(05) vcpu-0 - [vob.vmotion.net.get.swapbit.len.inval] vMotion migration [#######:###################] failed. Received invalid swap bitmap lengths from the source host <###.###.###.###>. source: 0, destination: #######.
Environment
- ESXi 8.x
- ESX 9.x
Cause
This issue is typically caused by a missing, locked, or misaligned Changed Block Tracking (CBT) file (-ctk.vmdk).
During the migration handshake, the source host reads a swap bitmap length of 0 (due to the invalid CTK state), while the destination host expects a valid non-zero length. This mismatch results in a "Bad parameter" error during the destination resume phase.
Resolution
Step 1: Reset Changed Block Tracking (CBT)
Resetting the CBT state often forces the host to recreate the tracking bitmap correctly.
Refer to Changed Block Tracking (CBT) on virtual machines for detailed CBT reset procedures.
Step 2: Storage vMotion (Workaround)
If the CBT reset does not resolve the error, the file lock or alignment issue may reside at the storage layer.
- Perform a Storage vMotion (migrate only the datastore, not the compute resource).
- This process migrates the disk files and recreates the associated metadata and tracking files on the target datastore.
- Once the Storage vMotion is complete, retry the regular vMotion (compute migration).
Additional Information
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