I have set up a Google Apps Scripts project with the intent of creating a Google Spreadsheets add-on with custom functions. However, when I use the option "Test as add-on", I can't use the functions that I created. When I paste the script code into the script editor opened from a spreadsheet it works fine, however.

Is this a limitation on how custom functions work in Spreadsheets, or am I simply doing something wrong?

  • 1
    The documentation offers only a cryptic remark: "Custom functions in Google Sheets use their own authorization mode, AuthMode.CUSTOM_FUNCTION, which is similar to LIMITED but has slightly different restrictions." No word about these slight differences. What does your custom function attempt to do?
    – user79865
    Commented Dec 14, 2015 at 20:13
  • There are quite a few custom functions. They all pull data from a REST API using UrlFetchApp (or the CacheService). However, even a function that simply returns a constant string does not work. It is not that the function gives an error, but it is unknown in the sheet: it results in a #NAME. Commented Dec 14, 2015 at 21:41

1 Answer 1


NOTE: This answer was cross-posted to Stack Overflow. I have made some updates there.


According to Eric Koleda in Code.gs - date_add_and_subtract to make available the custom fuctions in an add-on it's required to include at least one add-on menu, but this is not working at this time.


There are a couple of related GAS issues, please star them:

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