I'm trying to download the .publishsettings file from Azure's portal (at https://windows.azure.com/download/publishprofile.aspx) when I get that error message. Yes, I do have 10 management certificates (I have 2 hands too). However it's not clear what the connection between having 10 certificates and not being able to download the publish settings is. Why should the former prevent the latter and how can I still get the .publishsettings without deleting the other certificates from the Azure subscription?
I need this to supply the file to VS2012 (to publish) as well as for WebMatrix (again, to publish) and also for the Azure Powershell tools (again, to publish).
When you choose to download the publish profile it will create a new management certificate for you. If you look at the .publishsettings file you'll see that the management certificate is included in the file:
<?xml version="1.0" encoding="utf-8"?>
<PublishData>
<PublishProfile
PublishMethod="AzureServiceManagementAPI"
Url="https://management.core.windows.net/"
ManagementCertificate="AAAABAIBAzC...">
<Subscription
Id="XXXXXXXXXXXXXXXX"
Name="Sandrino" />
</PublishProfile>
</PublishData>
In order to generate a new publish profile you'll need to delete an existing management certificate (in the new portal this is possible under Settings).
If you don't want to delete an existing certificate, you can simply reuse a publish profile you previously downloaded. If you downloaded it once, you can keep reusing that publish profile until the certificate expires (1 year).