Script lab custom functions feature does not work - excel-addins

Question

When I try to access script lab custom functions feature I am greeted with message.
Script lab -> funtions
So the issue is not even in some particular function, the whole feature does not work.
Error:
{
"stack": "RichApi.Error: There was an internal error while processing the request.\n at new n (https://appsforoffice.microsoft.com/lib/beta/hosted/excel-win32-16.01.js:26:235928)\n at n.o.processRequestExecutorResponseMessage (https://appsforoffice.microsoft.com/lib/beta/hosted/excel-win32-16.01.js:26:299150)\n at https://appsforoffice.microsoft.com/lib/beta/hosted/excel-win32-16.01.js:26:297255",
"message": "There was an internal error while processing the request.",
"name": "RichApi.Error",
"code": "GeneralException",
"traceMessages": [],
"innerError": null,
"debugInfo": {
"code": "GeneralException",
"message": "There was an internal error while processing the request.",
"errorLocation": "CustomFunctionManager.register",
"statement": "v.register(...);",
"surroundingStatements": [
"var workbook = context.workbook;",
"var v = Microsoft.ExcelServices.CustomFunctionManager.newObject();",
"// >>>>>",
"v.register(...);",
"// <<<<<"
],
"fullStatements": [
"Please enable config.extendedErrorLogging to see full statements."
]
},
"httpStatusCode": 500
}

Answer 1

I've had this issue. I think I've seen there are differences between 2019 standalone and Office 365 subscriptions and the office js scripts that run. In my case, I was logged into a 365 enterprise subscription which reproduces the same error described. So what I did as a work-around was simply log out. And then register the function, and then log back in again. The registered function continues to work after log in.