Ever get an answer here?  I am running into the same issue

Please check the logs on the connection server first to see if you can find any more details about the error. 

You can find them in c:\programdata\VMware\VDM\logs\

Certainly a lot to pick through in the logs but the first mention of that error I see is as follows:

2022-09-01T11:23:13.774-04:00 DEBUG (180C-0B90) <DesktopControlLdap> [InformationBase] PoolInformation[cn=pc10-dvitest,ou=server groups,dc=vdi,dc=vmware,dc=int]::pae-PendingParentImageErrorMessage is now Fault type is AGENT_CUSTOMIZATION_FAULT - Internal template vm-101407 customization failed. Error description not set by agent.

Also check a few lines before and after the error. Most of the times something happened already before that caused that error.

Did you install the Linked clone feature during your Horizon Agent installation on your golden image?

No I did not.  We are just using instant-clones.  

Here are some errors I see prior

2022-09-02T13:02:15.761-04:00 ERROR (180C-200C) <WFE-03> [WaitForInternalTemplateAction] Internal Template Agent Customization Status: VM: vm-101453, Category: -1, Description: -1, Code: -1

2022-09-02T13:02:15.761-04:00 ERROR (180C-200C) <WFE-03> [WaitForInternalTemplateAction] Hit an error in waiting for internal template com.vmware.vdi.logger.Logger.error(Logger.java:96)

com.vmware.daas.cloneprep.common.CPAgentCustomizationException: Internal template vm-101453 customization failed. Error description not set by agent.

2022-09-02T13:02:15.762-04:00 WARN (180C-200C) <WFE-03> [Action] The VC Operation failed with error: com.vmware.daas.cloneprep.common.CPAgentCustomizationException: Internal template vm-101453 customization failed. Error description not set by agent.

2022-09-02T13:02:15.762-04:00 ERROR (180C-200C) <WFE-03> [Task] WaitForInternalTemplateAction of Task=[PrepareInternalTemplateTask:b8e13911-ed80-41a1-bf40-9b5aa0d327f1:1605], requestId=36384feb-2e6d-4678-a493-b025b910ec09 failed at index=5 with com.vmware.daas.cloneprep.common.CPAgentCustomizationException: Internal template vm-101453 customization failed. Error description not set by agent.

2022-09-02T13:02:15.762-04:00 DEBUG (180C-2184) <WFE-13> [Task] Skipping CreateSnapshotAction as Task=[PrepareInternalTemplateTask:b8e13911-ed80-41a1-bf40-9b5aa0d327f1:1605], requestId=36384feb-2e6d-4678-a493-b025b910ec09 has failed.

2022-09-02T13:02:15.763-04:00 INFO (180C-10E8) <WFE-20> [WorkflowEngine] Finished Task=[PrepareInternalTemplateTask:b8e13911-ed80-41a1-bf40-9b5aa0d327f1:1605], requestId=36384feb-2e6d-4678-a493-b025b910ec09. Task state: Failed

2022-09-02T13:02:15.763-04:00 ERROR (180C-04E0) <WFE-19> [Task] ExecuteMultipleTasksAction of Task=[PrimeInternalVmsTask:f0fea62f-f377-4307-bda7-90529b67acb0:1601], requestId=36384feb-2e6d-4678-a493-b025b910ec09 failed at index=2 with com.vmware.daas.cloneprep.common.CPAgentCustomizationException: Internal template vm-101453 customization failed. Error description not set by agent.

2022-09-02T13:02:15.766-04:00 DEBUG (180C-1CBC4) <PendingOperation-vm-93593:snapshot-101451-SchedulePushImage> [NgvcHelper] Progress report update for 36384feb-2e6d-4678-a493-b025b910ec09 : version=37 : FAILED : 18%

Sorry for my first question i read linked clone instead of lnstant clone.

I assume that you install this feature during the agent deployment on your gold image, right?

Are you selecting the correct snapshot during the deskpool deployment? Did you use sysprep or script for custom OS (like double nic in VM or something else)?

A DHCP server is a prerequsite to creating a Instant clone farm. 

Here's an article that might help:

Creating RDSH Automatic Instant Clone Farms - Notes_Wiki (sbarjatiya.com)

I'm having the same issue and I'm hoping this solves my problem because I dont have DHCP in my enviornment at the moment.

Sysprep for your gold imagae may have something to do with this issue as well.

Good luck.