Error 47: Error establishing HTTP connection (check HTTP port and firewall)



Error 47 is a FASP error that signals the following problems:

  • Problems establishing a FASP connection, likely due to UDP or TCP ports being blocked by a firewall on either the server or client
  • Problems establishing a fallback HTTP connection, likely due to the HTTP ports being blocked by a firewall on the server or HTTP fallback not being configured on the server

When a high speed transfer using FASP fails, Connect Server is able to retry the transfer using a traditional HTTP (TCP) connection. When even this method of transfer fails, the error 47 results.

Examples of this error

This error is mainly encountered when attempting transfers via the Aspera Connect browser plugin. For example, if you are at a Faspex or Shares site, or at a custom application site where you try to upload or download files, you will see the error in the Connect transfers window:



The same message appears when using Connect via the command line.


1. Unless internal policy requires ports to be closed, you should ensure the TCP ports for SSH and the UDP ports for FASP are open to traffic. If FASP-based transfers are being blocked you miss out on the biggest benefits of Aspera transfers, including high speeds and rate adjustment.

The default UDP port is 33001 and the default TCP port for SSH is 22, though you may have configured these to any port of your choice. Ensure traffic going in and out of these ports is allowed on both the client and server of your transfer.

On Windows, you must ensure that a range of UDP ports is not being blocked by a firewall. Because on Windows systems a single UDP port can’t be reused for multiple occurring transfers, each transfer makes use of its own UDP port (for example, in the range 33001-33020). Therefore, you should unblock a range starting at the configured UDP port up to the number of transfers you expect could occur simultaneously at any given time.

For more details on TCP/UDP ports and ranges, see the following Knowledge Base article: Firewall Considerations.

Below are some Knowledge Base articles that can guide you in testing your port connectivity and unblocking ports if necessary:

2. There may be instances when UDP or TCP ports are temporarily (or permanently) unavailable, in which case transfers will need to be conducted over HTTP.

First, ensure that HTTP fallback is properly enabled on your server. There are a few configurations you need to make in order to enable HTTP fallback, which can be done either through the server GUI or by editing aspera.conf. Details on the following needed configurations can be found in the Connect Server product manual:

  • Enable either the HTTP port or the HTTPS port
  • Specify the HTTP port or the HTTPS port (by default, these are set to 8080 and 8443 respectively)
  • Enable tokenization by setting a token key and configuring the transfer user to use tokens for inbound and outbound connections. If your transfer is being made through Faspex or Shares, tokenization should already be taken care of.

3. If HTTP fallback is configured properly, check that the HTTP/HTTPS port you’re using is open.

For example, if you configured HTTP fallback to use the default HTTPS port of 8443, you want to make sure that your firewall isn’t blocking traffic to or from TCP port 8443.

Use the articles from step 1 to help you test the TCP port, and unblock it if need be.

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