KB ID 0001499
I see this a lot! Usually I assume I just need to change browser, here the error is in Chrome. You can see this if you attempt to upload an ISO file to a datastore, or attempt to deploy an OVF file.
The operation failed for an undetermined reason. Typically this problem occurs due to certificates that the browser does not trust. If you are using self-signed or custom certificates, open the URL below in a new browser tab and accept the certificate, then retry the operation.
If this does not resolve the problem, other possible solutions are shown in this KB article:
The client simply does not trust the certificate VMware is presenting, (it’s a self signed certificate). So we just need to trust the CA that issued it! Open your browser and navigate to the hostname/IP of the vCenter. From there choose “Download trusted root CA certificates“.
Your machine should download the certificates in a Zip file. Open and extract that file. Locate the security certificate and double click it > Install Certificate.
Next > Select “Place certificate in the following store” > Locate the “Trusted Root Certification Authorities” container, and select that > Next > Finish.
When prompted select “Yes” > OK.
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