When trying to add versions to layers, the task may fail with an error.

Failed to execute the script. Unable to perform the operation.  The Nutanix server has encountered a failure processing the request (500).  Error: internal server error.  Details: Error occurred while creating Disk image.
 

App Layering only understands the Prism Elements protocol.  This is the protocol used to communicate directly with Nutanix hosts and clusters.  Prism Central is a management system for multiple hosts and clusters, but the ELM cannot communicate with the Prism Central server.  In order to work with a Nutanix host, App Layering also requires access to the NFS share for storage containers.  Make sure you have added the ELM to the Filesystem Whitelist in your Prism console.

In Nutanix 5.0, there is only Prism Elements, so there is no problem.

For Nutanix 5.5, you must configure the connector to communicate directly to a host, and nt the Prism Central server.

For Nutanix AHV 5.6 and 5.7, the host needs to unregistered from Prism Central.  Nutanix 5.6 and 5.7 disables NFS access when a host or cluster is added to a Prism Central server.  So you must make sure the host or cluster that App Layering will be directly communicating with is not part of Prism Central.

See https://portal.nutanix.com/#/page/docs/details?targetId=Prism_Central_Guide-Acr_v4_6:mul_register_wc_t.html

NFS access to the hosts was returned in AHV 5.8 so App Layering can still connect to the hosts even they are managed by Prism Central.  If at all possible, we recommend upgrading to Nutanix 5.8.  You must still set the Connector to communicate only with a single host or cluster, but NFS will work properly and we will be able to perform layering operations.

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Problem Cause

Changes in Nutanix AHV 5.6 and 5.7 when managed by Prism Central disables all NFS access to the host/cluster and forces it through Prism Central.  App Layering requires NFS access to the host.