Failed faxes are, unfortunately, unavoidable. This article describes how to troubleshoot failed faxes that you are trying to send out of Cerbo.

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The system will show any failed faxes at the top right of the Schedule page, along with a brief failure message. The system will also send a notification via email to the email address on file for the user who sent the fax.

General Troubleshooting Steps:

  1. Unless the error message indicates an invalid fax number or similar, you would first try resending the fax. To do this, click on the fax to open it, and then click on the Resend option at the top. Then you would delete the "failed fax notification" on the schedule page by right-clicking on it and selecting the Delete option (doing so DOES NOT delete the underlying document(s)). If the fax fails again, you will get another notification.
  2. If the fax fails again, you can try calling the receiving fax number on your phone to check if it is a valid fax number (you hear a fax tone when you call, not a phone tree, "number not in service" message, busy signal, etc.).
  3. The longer a fax is, the more likely it is to fail. If you are sending a fax longer than 5 pages we recommend using the fax package feature, this will send the one cover page, with a URL for the receiver to login to download the document. See here for more info
  4. If you hear a fax tone when you call, it may be worth trying to resend again if the original error messages were busy signals or similar.
  5. Or, you may want to call the office you are trying to send the fax to, to confirm that you have the correct fax number and there are no issues with the receiving fax machine.

If you continue to be unable to send the fax, after several retries and confirming the fax number by calling it and by calling the office you are sending to, you can file a ticket with us by emailing support@cer.bo. Please detail any steps you have already taken, so that we can file a ticket with the fax carrier.

Sometimes ad-blockers, ad-on's or pop-up blockers can interfere with outgoing faxes.  Check to make sure ad-blockers such as uBlock are not interfering with the successful sending of your faxes.

Error: The system could not turn your documents into a fax.

"The system could not turn your documents into a fax. Make sure your documents contain no macros, that they are not password-protected, and that they are in our list of supported file types. Try breaking your fax up into smaller faxes and resending."


  1. Can you open each of the included documents within the browser directly from the patient's chart? If any show a password protection message, or have some other issue opening, that is likely the source of the problem. To fix this, you would need to delete the document (by right clicking) and re-upload a non-password-protected version.
  2. Look at the file sizesshown to the right of each document. The total file size of all documents, plus the cover sheet, should not exceed 20MB. Note that 1024KB = 1MB. 
    • Note that if you have many documents above 1MB in a patient's chart, that may indicate that you are scanning documents at too high resolution. See Optimizing PDFs and scans.
  3. Are you running Kaspersky or Avast anti-virus extension in your browser? Those can inject code into the fax that interferes with sending. You can either disable the extension, or disable the setting in the extension that causes code to be injected. In Kaspersky, that is done in the Kaspersky settings under Settings > Additional > Network > Inject scripts into web traffic to interact with web pages.

Fax Window/ Tab Does not Appear

If you select the option to fax a document or create a faxable/ printable/ saveable form, and nothing happens, generally that means a pop up blocker is preventing the window from appearing. Check your browser settings and make sure that pop ups are enabled for the EHR website.

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