When trying to access our Extension Manager on our Sandbox account, it just goes to an error page with the following: { header": { "status": { "code": "ERROR" }, "message": "Unexpected token: <", "extra_data": {}, "error_code": "SyntaxError" } } No new code was deployed, or that's where I'd start. The only thing was another admin, but non developer, turned some extensions on and off. What he was supposed to turn on/off shouldn't have caused any issues, so I'm thinking maybe he turned an extension on he shouldn't have by accident. Whatever happened, any ideas how I can fix this? Anything I could try in the file cabinet?? Thank you in advance.

It is a known issue. If you want to raise a support case, cite issue 732186

Ok, thank you. I started a support case near the end of my day yesterday, but was hoping to get it fixed asap, as it's urgent and the support reps shift doesn't start until I'm almost off for the day. Was hoping it was something I could tinker with in the file cabinet and fix. I'll add that issue to the case.

I think there is a workaround that works for some people but not others. You’ll have to ask your support rep about it