This document covers all the known error codes that are thrown by Aspera SDK components.  Some errors below have debugging information that may help in getting to the root cause of the problem.  If you find a solution or have helpful information you wish to share with others please email us the error code and the solution for debugging.

Knowlege Base articles (Support)

There is additional debugging information available in the Aspera Support Knowledge Base that may be of use. See Troubleshooting error codes and messages.

Error Codes

Number Name Description Message Retriable
1 ERR_FASP_PROTO Generic fasp protocol error fasp error No
2 ERR_ASCP Generic SCP error ASCP error No
3 ERR_AMBIGUOUS_TARGET Target incorrectly specified Ambiguous target No
4 ERR_NO_SUCH_FILE No such file or directory No such file or directory No
5 ERR_NO_PERMS Insufficient permission to read or write Insufficient permissions No
6 ERR_NOT_DIR Target is not a directory Target must be a directory No
7 ERR_IS_DIR File is a directory - expected regular file Expected regular file No
8 ERR_USAGE Incorrect usage of scp command Incorrect usage of Aspera scp command No
9 ERR_LIC_DUP Duplicate license Duplicate license No
10 ERR_LIC_RATE_EXCEEDED Rate exceeds the cap imposed by license Rate exceeds cap imposed by license No
11 ERR_INTERNAL_ERROR Internal error (unexpected error) Internal error No
12 ERR_TRANSFER_ERROR Error establishing control connection Error establishing SSH connection (check SSH port and firewall) Yes
13 ERR_TRANSFER_TIMEOUT Timeout establishing control connection Timeout establishing SSH connection (check SSH port and firewall) Yes
14 ERR_CONNECTION_ERROR Error establishing data connection Error establishing UDP connection (check UDP port and firewall) Yes
15 ERR_CONNECTION_TIMEOUT Timeout establishing data connection Timeout establishing UDP connection (check UDP port and firewall) Yes
16 ERR_CONNECTION_LOST Connection lost Connection lost Yes
17 ERR_RCVR_SEND_ERROR Receiver fails to send feedback Network failure (receiver can't send feedback) Yes
18 ERR_RCVR_RECV_ERROR Receiver fails to receive data packets Network failure (receiver can't receive UDP data) Yes
19 ERR_AUTH Authentication failure Authentication failure No
20 ERR_NOTHING Nothing to transfer Nothing to transfer No
21 ERR_NOT_REGULAR Not a regular file (special file) Not a regular file No
22 ERR_FILE_TABLE_OVR File table overflow File table overflow No
23 ERR_TOO_MANY_FILES Too many files open Too many files open Yes
24 ERR_FILE_TOO_BIG File too big for file system File too big for filesystem No
25 ERR_NO_SPACE_LEFT No space left on disk No space left on disk No
26 ERR_READ_ONLY_FS Read only file system Read only filesystem No
27 ERR_SOME_FILE_ERRS Some individual files failed One or more files failed No
28 ERR_USER_CANCEL Cancelled by user Cancelled by user No
29 ERR_LIC_NOLIC License not found or unable to access Unable to access license info No
30 ERR_LIC_EXPIRED License expired License expired No
31 ERR_SOCK_SETUP Unable to setup socket (create, bind, etc ...) Unable to set up socket No
32 ERR_OUT_OF_MEMORY Out of memory, unable to allocate Out of memory Yes
33 ERR_THREAD_SPAWN Can't spawn thread Unable to spawn thread Yes
34 ERR_UNAUTHORIZED Unauthorized by external auth server Unauthorized No
35 ERR_DISK_READ Error reading source file from disk Disk read error Yes
36 ERR_DISK_WRITE Error writing to disk Disk write error Yes
37 ERR_AUTHORIZATION Used interchangeably with ERR_UNAUTHORIZED Authorization failure Yes
38 ERR_LIC_ILLEGAL Operation not permitted by license Operation not permitted by license No
39 ERR_PEER_ABORTED_SESSION Remote peer terminated session Peer aborted session Yes
40 ERR_DATA_TRANSFER_TIMEOUT Transfer stalled, timed out Data transfer stalled, timed out Yes
41 ERR_BAD_PATH Path violates docroot containment File location is outside 'docroot' hierarchy No
42 ERR_ALREADY_EXISTS File or directory already exists File or directory already exists No
43 ERR_STAT_FAILS Cannot stat file Cannot collect details about file or directory No
44 ERR_PMTU_BRTT_ERROR UDP session initiation fatal error UDP session initiation fatal error Yes
45 ERR_BWMEAS_ERROR Bandwidth measurement fatal error Bandwidth measurement fatal error Yes
46 ERR_VLINK_ERROR Virtual link error Virtual link error No
47 ERR_CONNECTION_ERROR_HTTP Error establishing HTTP connection Error establishing HTTP connection (check HTTP port and firewall) No
48 ERR_FILE_ENCRYPTION_ERROR File encryption error, e.g. corrupt file File encryption/decryption error, e.g. corrupt file No
49 ERR_FILE_DECRYPTION_PASS File encryption/decryption error, e.g. corrupt file File decryption error, bad passphrase No
50 ERR_BAD_CONFIGURATION Aspera.conf contains invalid data and was rejected Invalid configuration No
51 ERR_INSECURE_CONNECTION Remote-host key Check Failed Remote-host key Check Failed No
52 ERR_START_VALIDATION_FAILED File Start Validation Failed File Start Validation Failed No
53 ERR_STOP_VALIDATION_FAILED File Stop Validation Failed File Stop Validation Failed No
54 ERR_THRESHOLD_VALIDATION_FAILED File Threshold Validation Failed File Threshold Validation Failed No
55 ERR_FILEPATH_TOO_LONG File Path/Name too Long for File System File Path/Name too Long for File System No
56 ERR_ILLEGAL_CHARS_IN_PATH Windows Path Contains Illegal Characters Windows Path Contains Illegal Characters No
57 ERR_CHUNK_MUST_MATCH_ALIGNMENT Chunk size/start must be aligned with storage Chunk Size/Start Must be Aligned with Storage No
58 ERR_VALIDATION_SESSION_ABORT Session aborted due to validation errors Session Aborted Due to Validation Error(s) No
59 ERR_UNDEFINED Should never happen, report to Aspera Undefined error No

Debugging Information

Error 11 - Session Initiation Failed

If you encounter Error 11 after upgrading to Connect Client 3.0, it is most likely the result of a source/destination-pair issue with versions of Connect Server prior to 3.1. Connect Server version 3.1 fully supports source/destination pairs.


  • To use Connect Client 3.0 against a pre 3.1 version of Connect Server, within your transfer spec, remove the destination attribute from each entry in the "paths" array. If you need to target a specific directory for all files, you may also use the destination_root parameter. Examples are provided below.
  • Once released, you may upgrade to Connect Server 3.1.
  • Although not recommended, you may also force clients to use Aspera Connect Client 2.8.X. This solution requires hosting the Connect Client 2.8.X on a server where your clients may access it. Please contact Aspera support if there is a reason you feel you must take this route.

Example Code Changes

Path array with the destination tag (remove destination tag).


Destination tag removed. Rename file and directory (can only have one file per transfer spec).


Destination tag removed. Add a new directory, but do not rename files.


Destination tag removed. Rename a directory, but do not rename files.


Error 16 - Failed to Open SSH Session

Check to make sure the remote host exists. i.e. Check configuration (aspera.conf, transferSpec, etc.) the IP address may have been specified wrong, or there may be a miss-spelt hostname. You should also check to make sure you are connecting to the correct port. i.e. Check configuration (aspera.conf, transferSpec, etc.) the port given from the Connect Server may differ to the correct port if the configuration file is incorrect. Finally, check to make sure the remote host is reachable and the port is open; you can do this by using telnet: telnet 22

Error 19 - Authentication Failure, Server Refused SSH Authentication

If you are receiving this error and you are using Token-based authentication then your problem (at this stage) is probably not your token. Connect Client must still authenticate to the Connect Server before an exchange of token takes place, this is done by using the SSH RSA Key exchange, by default this key will not be in your users directory - you must manually do this step.

  • Navigate to your Aspera var directory (in Linux this would be /opt/aspera/var)
  • View the contents of the cat It should look something like this:

    no-agent-forwarding,no-port-forwarding,no-X11-forwarding,no-pty ssh-dss AAAAB3NzaC1kc3MAAACBAOQpAcPqbjIjGCOx7Lo+fLjppxlcRGwkfLnin8GpcjJiRU4CQSkqC9PepNM2bKRZbDii84/X4OLVz/YWlhyWVxOmGRZxL yUDuPTXaZQR5xdq9eM88bSLe3m+0HzEvLfeRDd72/38vCHTFxF+5rR3lR8XCikEgBe8kCvcHqtqmzz5AAAAFQC8LMnqrMdxKJQmglVyX/utXHiaaQ AAAIA+g+0Q/jLMcbZe1zEJ9dpvi73MTrA/Ph48m3RROfd9S+dCYlPuLQpUJGveDYfY5kxYXXbLSNSrxAG5nayjcId57tbVWYB1s3sXFz5zJX2cTrN RGoBo/K3ZsT6uAzWk/otBRjGAPfEp2/Vkb6QMgMR/pTeieNwpuYDpyTFPoZq+gAAAAIEAobapDv5p2foH+cG5K07sIFD9r0RD7uKJnlqjYAXzFc8U 76wXKgu6WXup2ac0Co+RnZp7Hsa9G+E+iJ6poI9pOR08XTdPly4yDULNST4PwlfrbSFT9FVhzkWfpOvAUc8fkQAhZqv/PE6VhFQ8w03Z8GpqXx7b3 NvBR+EfIx368Ko= Aspera public access
  • Copy the content of this file into the authorized_keys file of your transfer users .ssh directory
    • If your transfer user was 'aspera', you would navigate to /home/aspera/.ssh (for Linux)
    • Add to the file (or create) authorized_keys the contents of the file cat
      • If you create this file, be sure to check the permissions of the file and the folder .ssh
      • If the permissions are not correct you can fix it with the commands:
        • chown aspera /home/aspera/
        • chown aspera /home/aspera/.ssh/
        • chown aspera /home/aspera/.ssh/authorized_keys
        • chmod 755 /home/aspera/
        • chmod 755 /home/aspera/.ssh/
        • chmod 755 /home/aspera/.ssh/authorized_keys
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