ads.txt Errors in GAM

How to resolve the three common GAM ads.txt warnings — missing file, missing seller entries, and invalid format — and how long it takes GAM to re-check after you fix the file.

Google Ad Manager periodically checks your ads.txt file and reports any issues in the Admin → Ads.txt section of your GAM account. This article explains the most common error types and how to resolve them.

Common GAM ads.txt warnings

"Your ads.txt file is missing or inaccessible"

Cause: GAM cannot fetch https://yourdomain.com/ads.txt. Either the file doesn't exist, your web server is returning a non-200 response, or the file requires authentication.

Fix:

Verify the file exists at your domain root by visiting https://yourdomain.com/ads.txt in a browser.
Ensure the web server returns HTTP 200 (not a redirect loop or 403).
Check that the file does not require login to access — it must be publicly readable.

"ads.txt is missing entries for authorized sellers"

Cause: Your file is present but does not include the necessary lines for all demand partners connected to your inventory through Advlume.

Fix: Download the latest version of your personalised ads.txt from Dashboard → [site name] → Settings → ads.txt and replace your existing file with the new version. This is the most common cause of this warning.

"Invalid file format"

Cause: The file contains characters or formatting that GAM cannot parse. Common causes: the file was saved with a BOM (byte order mark), Windows-style line endings (CRLF) are causing parsing issues, or the file contains non-standard characters.

Fix: Open the file in a plain text editor (not Word or Pages), ensure it uses Unix line endings (LF), and save it as UTF-8 without BOM. On macOS or Linux, you can regenerate it directly from the dashboard and download the file rather than copying and pasting.

"Authorized sellers entry contains incorrect domain"

Cause: The Advlume reseller entry in your file has a typo in the domain field, or the file was generated for a different publisher and has a different seller ID.

Fix: Regenerate your personalised file from the dashboard — do not manually edit the Advlume entry lines.

After fixing

GAM checks ads.txt files periodically (typically every 24–48 hours). After uploading a corrected file, it may take up to 48 hours for GAM to re-check and clear the warning. Demand partner suppression related to the missing entry typically lifts within a few hours of GAM confirming the fix.