[Help] Backup failed with error #3436 when using CBT on XenServer

Elias Blackwood

Hi everyone,

Has anyone encountered this issue before? I'm trying to perform a VM backup on XenServer with CBT enabled, but the task fails with the following error:

Description:
Using CBT feature in XenServer VM backup failed with error code #3436
Error Code:
#3436 Xapi Error: This operation is not allowed under your license (CBT backup failed)

Would really appreciate any input or suggestions. Thanks in advance!

Elias Blackwood

and this is the photo

Everett Kensington

Hi,

You're welcome!

Root Cause:
Only XenServer Enterprise and Platinum editions support the CBT feature.

Resolution:
You can try changing the Incremental Mode to SpeedKit or Ordinary when creating a new VM backup job:
Backup > Backup Strategies > Advanced Strategy > Incremental Mode,
then run the backup again.

Hope this helps!

Elias Blackwood

Everett Kensington Thanks! Now I know how to fix it 👍
Will switch the Incremental Mode and try again.

Elias Blackwood

Everett Kensington By the way, just to clarify — will switching to SpeedKit affect backup performance or storage usage in any noticeable way?

Appreciate your help as always!

Everett Kensington

Elias Blackwood Great question!

Switching to SpeedKit may actually improve backup performance, especially for larger VMs, as it uses a more optimized method to detect changes.
As for storage usage, it’s generally efficient. That said, depending on your VM’s data change rate and activity, the size of incremental backups may vary slightly compared to CBT.

Reid Montague

wow,cool