Errors can occur during downloads or uploads of VMware virtual machine configuration files.
Symptom
The following errors can occur when transferring configuration files:
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A backup job fails with one of the following errors:
Error downloading virtual machine config file.Unable to download VMX files. -
The following error message is displayed when trying to download a .vmx file from a datastore through vCenter:
Error code: 91:29 - Unable to download the VMX file for virtual machine [...].
Cause
Issues can occur for several reasons:
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Downloads or uploads can fail because of connectivity issues or high usage in vCenter.
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The names of one or more virtual machines, datastores, or clusters included in a backup contain the following characters:
- & @ % = # % * $ # ! \ / : * ? " < > | ; '
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The management agent on the ESX host might need to be restarted.
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For vCenter 4.0 or 4.1, updates might need to be installed.
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Failure when trying to download a .vmx or .nvram file from a datastore through vCenter is an identified VMware vSphere VADP issue. The vCenter client datastore browser connected to vCenter server fails to download .vmx or .nvram files.
For more information, see Using the vCenter Server 4.x/5.x datastore browser to download or copy a powered-on virtual machine's .vmx and .nvram files fails (1019286).
There is an identified issue for VMware and Windows 2008 R2 Enterprise; the issue was resolved for other Windows operating systems in versions 4.0 U2 and 4.1.
Resolution
To resolve the issue, check the following items:
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Check the communication between the vCenter server and the host.
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If the names of any virtual machines, datastores, or clusters contain invalid characters, rename the entities so the following characters are not used:
- & @ % = # % * $ # ! \ / : * ? " < > | ; '
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For ESX 5.5 and later, you can use the nUseHTTPTicket additional setting to enable downloads and uploads of VMware VM configuration files to go directly to the ESX host instead of through the vCenter Server. If the request cannot go directly to the ESX host, the request automatically falls back to going through vCenter.
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If required, restart the management agent on the host. For more information, see Restarting the Management agents on an ESXi or ESX host (1003490).
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If you have the 4.0 or 4.1 version of vCenter , ensure that the latest updates are installed on the vCenter. For more information, see Using the VMware vCenter Server 4.x/5.x datastore browser to download or copy a powered-on virtual machine's .vmx and .nvram files fails (1019286).
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Failure to download .vmx and .nvram files from vCenter can be resolved by installing vCenter Server 4 update 2.
VMware strongly recommends upgrading the vSphere ESX 4.0 host servers to Update 2 at the same time the vCenter Server is upgraded.
For more information, see VMware vCenter Server 4.0 Update 2 Release Notes
Without Update 2, the vCenter Server does not know which ESX host has the VMX file locked.
If you are unable to install that update, you can resolve this by creating identical credentials directly on the ESX host. For example, if your vCenter user is "cvbackup" you would need to create an ESX user named "cvbackup".