Getting 'Precondition check failed' error when listing emails with Gmail API

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1

Help! Gmail API is giving me trouble

I’m building a .NET 8 app with Razor pages and I’m trying to use the Gmail API. I’ve got the user to sign in and I’m storing their token in my database. I can even get a new access token using the refresh token. But when I try to get the user’s emails, I keep hitting a wall.

Here’s what happens:

  1. I get a new access token - this part works fine.
  2. I try to fetch the emails using the new token.
  3. Boom! I get a 400 Bad Request error saying ‘Precondition check failed.’

I’ve double-checked my code and I’m pretty sure I’m using the API correctly. The scope includes ‘gmail.readonly’, so that should be okay too.

Has anyone run into this before? Any ideas what might be causing it? I’m kinda stuck here and could really use some help figuring out what’s going wrong.

Thanks in advance!

2

I encountered a similar issue when implementing Gmail API in a project. The ‘Precondition check failed’ error often stems from token-related problems. Have you verified the token’s expiration? Even if you’re refreshing it, there might be a timing issue. Also, ensure you’re using the correct API version and that all required headers are included in your requests. Another potential cause could be rate limiting - if you’re making too many requests in quick succession, Google might temporarily block access. Consider implementing exponential backoff in your code to handle this gracefully. Lastly, double-check your API console settings to confirm all necessary APIs are enabled for your project.

3

hey there, i’ve seen this before. it’s usually caused by a mismatch between the token and the account you’re trying to access. double-check that the token is for the right gmail account. also, make sure your app’s credentials in the google cloud console are set up correctly. hope this helps!

4

I’ve dealt with this exact issue in one of my projects. The ‘Precondition check failed’ error can be tricky to diagnose. One thing that solved it for me was ensuring that the user’s consent was up-to-date. Sometimes, Google’s security measures kick in, and you need to re-authenticate the user.

Try implementing a check for the GoogleApiException with the status code 401 or 403. If you catch this, prompt the user to re-authorize your app. This approach helped me resolve the issue and maintain a smoother user experience.

Also, make sure you’re using the latest version of the Google.Apis.Gmail.v1 NuGet package. Older versions sometimes have quirks that can cause unexpected behavior with token handling.