Youtube Post: Fix Guide: “Access blocked: Request is invalid” (Error 400: redirect_uri_mismatch)
Use this troubleshooting guide to isolate the issue, apply one controlled fix, and verify the same workflow again.
Use this guide
- Confirm the symptom and copy the exact message shown.
- Check the prerequisites named in the detailed steps below.
- Apply one change at a time, retry the same test, and record the result.
Detailed steps
⚠️ Fix Guide: “Access blocked: Request is invalid” (Error 400: redirect_uri_mismatch)
If you see this Google error while connecting your YouTube account:
Access blocked: [App Name]’s request is invalid
Error 400: redirect_uri_mismatch
it means your Redirect URI in Google Cloud Console does not match the one used by Stackposts.
🔹 Step-by-Step Solution
1️⃣ Go to Google Cloud Console
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Log in with the same Google account that created your YouTube API project.
2️⃣ Open Your OAuth 2.0 Client
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Under OAuth 2.0 Client IDs, click the name of your app.
(It looks like your Client ID starts with:460228741010-7m2ttd3fj76jrk8bbyjn84vr45m06jst.apps.googleusercontent.com)
3️⃣ Check “Authorized redirect URIs”
Scroll down to Authorized redirect URIs, and make sure it includes the exact URL from your Stackposts YouTube settings:
💡 Example (from your screenshot):
⚠️ The URI must match exactly — including
https://,/app/youtube/channel, and no extra slashes.
4️⃣ Save Changes
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Click Save at the bottom of the Google Cloud Console page.
5️⃣ Retry Connection
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Return to your Stackposts panel → YouTube API settings.
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Click Save changes, then try connecting your YouTube channel again.
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The Google sign-in window should now work without the redirect error.
🔹 Common Mistakes to Avoid
| Problem | Cause | Fix |
|---|---|---|
Missing /channel at the end |
Redirect URL incomplete | Use the full callback: /app/youtube/channel |
| Wrong domain (e.g. localhost, staging) | Google only allows pre-approved URIs | Add each environment domain in “Authorized redirect URIs” |
| HTTP instead of HTTPS | Google requires SSL for OAuth | Use https:// |
| Copy/paste error | Hidden space or typo in the URI | Copy directly from Stackposts’ purple “Callback URL” field |
Quick check
- The save or publish action completes without an error.
- The visible status, preview, or connected account matches the change.
- If the result differs, capture the exact message and review the troubleshooting guidance before retrying.