Troubleshooting “failed to parse message” errors

When using Proton Mail Bridge, you may encounter this error when attempting to send a message from your email client.

Essentially, this error flags when the message could not be parsed for sending — likely due to some part of the message containing invalid information.

How to troubleshoot “failed to parse message” error

Depending on the issue, you will receive different variations of this error message. Below, we will cover the most common ones.

failed to parse to/cc/bcc

Example error: failed to parse message: failed to parse message header: failed to parse to: [Error offset=52]: expected " for quoted string end

This error message flags when one of the recipients is invalid. To resolve the issue, make sure to double-check the recipients of your message and ensure they all have valid addresses.

Classic Outlook

In Outlook, you can add a recipient by providing a name rather than an address. This does not work in Bridge, however, as Bridge has no way to associate those names with an email address, so an error message will be returned.

To resolve the issue, you can try to enter the recipients manually without allowing Outlook to auto-complete the results. This should ensure that the addresses are entered.

‘failed to collect attachments’

Example error: 554 5.0.0 Error: failed to parse message: failed to collect attachments: mime: no media type

This error is triggered when attachments can not be processed correctly. To resolve the issue, you can test if it happens with other attachments as well. In some cases, it might also work to zip the attachment and attach the zip file to the message.

Other variations of the errors

While there can be other variations of the “failed to parse” error message, these are the most common ones. As these errors can sometimes be difficult to diagnose, feel free to contact our support team for further assistance.