Troubleshooting Remote Server Sync

There a several issues that can cause remote sync failures, such as authentication issues or firewall issues on remote server; general connectivity issues on the remote server; invalid file or folder names, invalid file sizes; slow transfer times; file/folder not found; and even partial failures

When these issues occur, you may see effects such as some files successfully being transferred while others fail. We provide detailed error messages that should allow you to determine the cause of the failure.

Authentication or Firewall Issues

Authentication issues can usually be resolved by correcting any relevant credentials. However, sometimes authentication issues can occur because of IP address requirements.

Be aware of the following if the remote server enforces an IP address whitelist

If your site uses a custom domain, you have two dedicated IPs that may be used for outbound connections. You can find your dedicated IPs by typing "Firewall**"** in the search box at the top of every page and then clicking the matching result. Scroll to Firewall configuration. You can disable the use of your dedicated IP in the settings for each individual sync. (You might do that if your counterparty has already whitelisted the main IP range, for example.)

If you do not have a custom domain, ensure that our main IPs on this list are whitelisted, not just some of them. There are quite a lot of IPs on that list (over 80 at last count) and you need to whitelist all IPs or else you will experience failures. If whitelisting that many IP addresses is a problem for you, the solution is to move to a custom domain. This will get you a pair of IP addresses you can whitelist (see the prior bullet.)

Invalid File or Folder Names

Remote servers will likely prohibit certain characters from being used in file and folder names. If you see issues with invalid file or folder names, we recommend you modify those names to remove the restricted characters.

Remote servers may also restrict the length of the file or folder name. Common length limits include:

  • 160 characters
  • 255 characters

Bear in mind that some remote servers calculate the total length as being either just the file or folder name, including any extension OR the sum of the whole folder path + file name + extension + temporary suffix

To resolve this issue, shorten the name of files and folders so that they are below the length limits of the remote server.

On the side, the path limit is 550 characters for the length of the full path, including folder names.

Invalid File Sizes

Remote servers may have maximum size limits for files. Please check the documentation of the remote server for details on any file size limits or restrictions.

Remote servers that use APIs or HTTP based connections may also not support zero byte file sizes (for example, you can not pull zero byte size files from Azure storage).

Slow Transfer Times

Slow transfers and long transfer durations can be caused by low network bandwidth, high network latency, large quantity of files being transferred, huge file sizes, network throttling, remote system performance, local system performance, encryption methods, and session time limits.

The physical limitations of a network or system cannot be circumvented. For example, if sending a 10GB file across the internet to the remote server takes you 2 hours then sending the same 10GB file across the internet to the remote server will take us 2 hours also, assuming we both have identical network connectivity with the remote server.

Remote Server Issues

If the remote server has a temporary issue, such as being temporarily offline or unavailable, then the current sync will fail but subsequent scheduled syncs will retry until all syncs have been completed.

If the remote server has a permanent issue or limitation, such as not accepting file sizes greater than 2GB or having the incorrect access permissions set, then affected files will never be successfully transferred and subsequent runs of the sync will keep repeating the transfer attempt and will keep showing failure outcomes in the logs.

To resolve these issues, make sure that the correct access permissions have been set on the remote server and that any known limitations are communicated to your users. For example, if the remote server cannot accept file sizes greater than 2GB then communicate to your users that file sizes should be kept below the 2GB limit.

To troubleshoot access permission issues, configure a connection to the remote server using credentials with full (read, write, update, delete, list, etc.) access permissions and see if the issue persists. If not, then an access permission is causing the issue. Reconfigure the access permissions one at a time and re-test the sync to determine exactly which access permission is causing the issue.

Connection Timeout

If the connection to the remote server times out then the current sync run will finish and report a Failure or Partial Failure error.

Subsequent syncs will attempt to continue transferring the remaining files, omitting those files that have already completed successfully.

Much like the slow transfer times issues, if the transfer duration is longer than the connection timeout, then the next run could restart the transfer over from the beginning, causing an endless retry loop where the file never gets completely transferred to the remote server.

To resolve this issue, contact the administrator of the remote server and ask if they can configure a longer connection timeout duration or limit the file sizes of your files so that they can be fully transferred within the duration of the connection.

File/Folder Not Found

This error message can occur when a target file or folder has been deleted, moved, or renamed, between the time the sync started and the time that the file is reached.

For example, a sync is processing 1000 files. The sync generates a list of the names of the 1000 files and begins processing them. However, file number 999 is renamed during the processing. When the sync reaches file 999 it will not find it as its name has changed and an error is logged. A subsequent sync should pick up the renamed file, assuming it isn't renamed, deleted, or moved again.

Partial Failure

A partial failure error message indicates that some of the files were processed successfully and some were unsuccessful.

Look at each of the log messages for the individual files that failed to sync to determine which of the above issues caused the failure for that file.

Partial failures can be caused by multiple issues, so check each failed file to determine each cause.

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