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Troubleshooting ads.txt and app-ads.txt Issues

What is ads.txt and why does it matter?

The ads.txt (Authorized Digital Sellers) and app-ads.txt standards, developed by the IAB Tech Lab, help publishers protect their inventory from unauthorized reselling and ad fraud.

These files declare which companies are officially authorized to sell your ad inventory whether on your website or within your mobile app.

Having a correctly implemented ads.txt or app-ads.txt file helps:

  • Increase transparency for advertisers and demand partners.
  • Build trust in your inventory.
  • Maintain strong programmatic ad revenue.

If your file is missing, incomplete, or incorrectly formatted, advertisers may block your inventory, resulting in lower ad fill rates and reduced revenue.

How to Check if Your ads.txt or app-ads.txt File is Correct

Clickio provides an integrated ads.txt validator directly on the platform. You can also use public validators to confirm that your file is correct and up to date.

To check your file:

1. Visit your file in a browser, for example:

    • Websites: https://domain.com/ads.txt
    • Apps: https://yourappdomain.com/app-ads.txt

2. Ensure the file loads correctly and contains the latest authorized lines.

3. Use the Clickio Ads.txt tab to check the file status and receive automatic alerts about issues.

4. Optionally, you can use a free validator to check for syntax or formatting errors.

Common ads.txt / app-ads.txt Errors and How to Fix Them
1. File placed outside the root domain

Your ads.txt file must be hosted on the root domain (e.g., https://domain.com/ads.txt), not on a subdomain (e.g., https://blog.domain.com/ads.txt).

If needed, set up proper redirects from subdomains to the root domain.

2. app-ads.txt file not hosted on developer domain

For mobile apps, the app-ads.txt file must be uploaded to the developer’s website domain listed in your App Store or Google Play listing.

If your app uses a different domain or redirects incorrectly, demand partners may not verify it.

3. File blocked by robots.txt

Make sure your robots.txt file does not block crawlers from accessing ads.txt or app-ads.txt.

Your robots.txt should allow both the file path and the relevant User-Agents (Google and other demand partners).

Example of a correct configuration:

User-agent: *

Allow: /ads.txt

Allow: /app-ads.txt

4. Formatting or syntax errors

Use a plain text editor when editing your ads.txt file.

Avoid special characters or formatting such as tabs, extra spaces, %, or quotes.

Each line should follow this structure:

<ad system domain>, <publisher ID>, <relationship type>, <certification ID (optional)>

5. File not accessible via both HTTP and HTTPS

Google and other crawlers may attempt to reach your ads.txt or app-ads.txt via both HTTP and HTTPS.

Ensure the file is publicly accessible via both protocols, or set up proper redirects from HTTP to HTTPS.

6. File not returning “HTTP 200 OK” status

If the server returns an error code (e.g., 404, 403, or 500), crawlers will treat the file as non-existent.

Check your server configuration to make sure the file returns a 200 OK response.

Best Practices
  • Keep your file up to date whenever you add or remove ad partners.
  • Verify that the file is reachable and readable by crawlers.
  • Use the Clickio validator regularly to detect missing or incorrect lines.
  • Don’t delete existing lines when adding new ones, this can interrupt ad serving.
  • For apps, make sure the developer website URL in your app store listing matches the domain where app-ads.txt is hosted.
FAQ — ads.txt and app-ads.txt Troubleshooting

1. What happens if I don’t have an ads.txt or app-ads.txt file?

Without it, many advertisers may block your inventory, leading to lower fill rates and decreased revenue.

2. How can I confirm that Clickio is included in my ads.txt file?

Open your file and look for lines that reference Clickio’s authorized seller entries. If missing, log in to your Clickio dashboard to copy the correct entries.

3. My ads.txt is correct but I still see warnings. What should I do?

Sometimes it takes up to 24 hours for validation to update. If the issue persists, contact support@clickio.com.

4. How can I check if the file is indexed by crawlers?

Search for your file on Google (e.g., site:domain.com ads.txt). If it’s not visible, check robots.txt or server accessibility.

5. What else should I check for correct ad serving?

  • Make sure your ads.txt or app-ads.txt includes all necessary Clickio lines.
  • If your site or app receives EU/UK traffic, ensure a Consent Management Platform (CMP) is installed and configured correctly.
  • Keep your Clickio header code or SDK up to date for accurate tracking and ad delivery.
If you still experience problems with your ads.txt or app-ads.txt file, contact your Clickio Account Manager or email support@clickio.com, our team will assist you in resolving the issue quickly.
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