Detailed steps

✅ Fixing Google Drive “The API developer key is invalid” (Google Picker Error)

This error comes from Google Picker, not Google Drive.
Google Picker requires a valid API Key, and if the API Key is missing, incorrect, or restricted, you will see:

The API developer key is invalid

To fix this, follow the instructions below.

🔧 Step-by-Step Setup Guide (Google Drive + Google Picker)

1️⃣ Enable Required Google APIs

Go to Google Cloud → APIs & Services → Library
Enable these APIs:

• Google Drive API

• Google Picker API

• (Optional) Google People API

2️⃣ Create Required Credentials

Go to Google Cloud → APIs & Services → Credentials

You must create three items:

✔ A. API Key

Used by Google Picker popup.

✔ B. OAuth Client ID

Used to log in with Google Drive.

✔ C. OAuth Client Secret

Also used for OAuth login.

3️⃣ Configure the OAuth Redirect URI

Copy the redirect URL from your Stackposts settings, for example:

Paste it into:

Google Cloud → Credentials → OAuth Client → Authorized redirect URIs

4️⃣ Configure the API Key (IMPORTANT)

Your API Key must be:

• Active

• Not restricted incorrectly

• Allowed to use Google Picker + Drive API

If you want to restrict it, use:

Application restrictions:
→ HTTP referrers (websites)

Allowed domains:

🎉 After Completing These Steps

Google Drive will login correctly using OAuth,
and Google Picker popup will work using your API Key,
so the error:

"The API developer key is invalid"

will disappear.