Users of Google Drive can sometimes see Error 403 (permission denied) or Error 404 (not found). There are a few common reasons for this:
- You are not the owner of the document but this is a shared document owned by a different Google account. Check your document sharing permissions on Google.
- You have multiple Google accounts (let's call them Acct1 and Acct2); your spreadsheet is owned by Acct1 but you sign into AppSheet using Acct2 to access the spreadsheet. Either use the same account, or share the document across accounts.
- You had access to the file at one point, but the access has been removed.
- This can sometimes occur if you have a corporate Google Docs account that has an admin policy that prohibits all users from enabling third party software like AppSheet (so you may need to talk to your account admin).
If you use on of the AppSheet add-ons to integrate with Google Forms, Sheets, or Docs, please also read this article to learn more about specific limitations in those integrations.
In particular, if you utilize Google AppScript onEdit triggers on your Google Sheet, or a third-party addon that utilizes these triggers, those triggers are not fired when AppSheet makes a change to the data in the spreadsheet. This is an unfortunate limitation imposed by Google on all third-party solutions like AppSheet. The best workaround is to utilize a timed AppScript trigger rather than an onEdit trigger.
Also, do not use filters on your Google Sheets --- it can make the filtered rows invisible to updates. Instead, use filter views (this is a Google Sheets feature that lets each user create and use their own filters without affecting other users of the sheet).
Make certain that your spreadsheet is not marked as "Public". The Google spreadsheets API doesn't enable updates against public spreadsheets.