Your Header Bidding script (M2HB) is not loading asynchronously.

Step 1: On your webpage, right-click ‘view page source’.

Step 2: Search for ‘m2d’ to locate the Off-page header bidding header script, or ‘async’ if using an On-page setup.


Step 3: The header should be coded as async. Sample Off-page header implementations that work (first one below being the recommended format):

  • <script src=”//” async></script>
  • <script async src=”//”></script>
  • <script async=true src=”//”></script>

Here is a sample async On-page header:

source code

Step 4: If you don’t see an async setup, provide instructions to your publishing team to correct the header script.

Step 5: If the implementation is correct and you still see this error in the configuration test please report this to our support team with this notification title in the subject line and they’ll help you troubleshoot the issue.

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