Why AdMob Keeps Rejecting Your App-ads.txt (The "Invisible Character" Bug)
Is your AdMob fill rate zero? It might be a hidden formatting error in your app-ads.txt file. Learn how to validate your file headers and fix rejection instantly.
If AdMob cannot verify your app-ads.txt, your ad revenue drops to zero. The most common cause is not the text itself, but the encoding of the file. Web servers like Vercel or Netlify often serve text files with the wrong HTTP headers.
⚠️ The Nightmare Scenario
"I recently lost a chunk of revenue because my AdMob account couldn't verify my domain. The file looked fine in Chrome—I could see my publisher ID perfectly. But the crawler rejected it."
The Solution (Curl Command)
Run this in your terminal:
curl -I https://yourdomain.com/app-ads.txtIf the Content-Type says text/html instead of text/plain, AdMob will reject it. This often happens when you put a text file in a Next.js public folder without configuring the headers.
Common Mistakes That Break app-ads.txt
Wrong Content-Type Header
Server sends file as text/html instead of text/plain. This is the #1 cause of rejection.
Hidden Unicode Characters
Copy-pasting from Word or PDFs adds invisible BOM (Byte Order Mark) characters that corrupt the file.
Wrong File Location
File must be at yourdomain.com/app-ads.txt (root level), not in a subdirectory.
SSL Certificate Issues
AdMob crawler requires HTTPS. HTTP-only domains get rejected automatically.
How to Verify Your File is Correct
- 1
Check Content-Type
Run
curl -I https://yourdomain.com/app-ads.txt - 2
Validate Format
Use Google's app-ads.txt validator tool to check syntax
- 3
Test Encoding
Open file in a hex editor to check for BOM characters (EF BB BF at start)
- 4
Wait 24 Hours
AdMob crawler checks once per day. Changes take time to propagate.
The Fix
I built Launchinseconds to solve this specific engineering headache. We auto-generate your app-ads.txt and host it with the exact headers and encoding Google requires. Stop debugging text files and start earning revenue.
✓ Automated Solution
Launchinseconds automatically generates, hosts, and maintains your app-ads.txt with correct headers, encoding, and format—guaranteed to pass AdMob verification.
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