Message: An internal error occurred during execution, please contact Vizioncore support if the error persists. Error Message: API Call failed with message: Cannot create a quiesced snapshot because the (user-supplied) custom prefreeze script in the virtual machine exited with a nonzero return code.
Could be error in the batch file
Problem with COM+ System Application or VSS on the VM you are trying to backup wiht Quescing enabled.
Please check for mistakes in the script/batch file.
If this is not the case follow those steps:
Verify that VSS is working by running
vssadmin list writers
vssadmin list providers.
and then in the services.msc list of services snapins, make sure the following services are Started Automatically:
1. COM+ System Application
2. Distributed Transaction Coordinator
3. Volume Shadow Copy
4. VMware Physical Disk Helper Service
Automatically but not started:
1. Microsoft Software Shadow Copy Provider
2. VMware Snapshot Provider
Here are a couple of articles that discuss this issue: