"Error: API Permission Failed." in ET_Get.php

[maskedjellybean]

I don't think this is a bug, but I'm hoping someone can tell me what I'm doing wrong. Line 78 of ET_Get.php always returns:

At line 78 $authstub is:

I'm trying to fix an implementation of ExactTarget/Marketing Cloud that is a few years old and recently randomly stopped working. I've narrowed down the failure to this line but I don't know what to make of the vague error message.

Does anyone see anything obviously wrong with $authstub? One thing that I thought was odd is that $authstub->tenantKey is null. I can't find any documentation on what tenantKey should be or how to set it. Is it the same as the 28 char string described here? https://help.salesforce.com/articleView?id=mc_rn_october_2018_platform_tenant_specific_subdomains.htm&type=5

So far I've tried:

• Updating the SDK from .9 to 1.3.0, but I found this call fails in both versions with the same message.
• Using the tenant specific domain endpoints described here: https://developer.salesforce.com/docs/atlas.en-us.mc-apis.meta/mc-apis/wsdl-endpoint-links.htm
• Passing 'tenantKey' equal to my tenant specific domain 28 char string as part of $config when instantiating new ET_Client().

Any help would be appreciated. I can provide whatever information would be helpful.

Environment

• SDK Version [e.g. 1.3.0]
• PHP version 7.1.28