A new feature: Allow for certificates to be specified in the AzureCloudPowerShellDeployment task settings (in the "Advanced Options For Creating New Service" section, similar to the "Diagnostic storage account keys" setting) in a Release definition.
Server - VSTS or TFS on-premises?
Does NOT depend on the cloud/on-premise environment.
Agent - Hosted or Private:
Does not depend on the Agent type.
Task AzureCloudPowerShellDeployment should be able to support certificates for creating a new Azure Cloud Service instance. Without the support for certificates, the task fails when it tries to create a new ACS and then deploy the ACS which does use custom certificates.
2018-02-13T08:55:01.4184581Z ##[error] BadRequest: The certificate with thumbprint 58e54ffab7...........a5 was not found.

I am willing to implement this if the feature is accepted.
@ross-bohr
It refers to certificate within the cspkg. Can you please check if certificate is valid.
Also, can you please share debug logs at [email protected] . Debug logs you can enable by adding RD variable System.debug = true
@Ajay-MS , the error shown above is related to a certificate that the ACS is using. It is listed in the ACS Cloud config as:

This is a certificate which the ACS starts using as soon as it boots up. It must be present in the ACS definition (in the certificates list) , otherwise the deployment of the ASC roles fails with the above error.
Effectively, this makes the procedure to deploy a new ACS as follows:
This is not the optimal experience as one would like to automate the ACS creation end-to-end. Thus, I'm proposing this new feature to allow for the VSTS/TFS task to include the list of required cert(s) (by the ACS) as a string of ["base64StringOfCertPfx":"securedVariableForCertPassword"]
Sounds good to me. I will discuss this with PM and will update you by tomorrow on this.
@ross-bohr
We will be happy to have a contribution from you. Let me know as soon as you are done with your PR for this feature.
Thanks in advance.
@Ajay-MS
Please find my PR for this feature here https://github.com/Microsoft/vsts-tasks/pull/6467
Please advise how to provide the translations for the other languages besides en-US.
Thanks in advance.
@ross-bohr Thanks for your contribution. You dont need worry for translation, our system will take care of it.
@Ajay-MS to proceed with PR
@ross-bohr thanks for your contribution. @Ajay-MS has taken care to merge this.
The changes will be available with next deployment