How to Fix: rsync --append or --append-verify flags causing transfer to error on resume

The error 'rsync: [sender] write error: Broken pipe (32) rsync error: error in socket IO (code 10) at io.c(823) [sender=3.2.3] rsync error: received SIGUSR1 (code 19) at main.c(1595) [generator=3.2.3]' occurs when the append-verify or append flags are used with the rsync command, causing the transfer to fail even if the connection is dropped mid-way.

This issue can be frustrating for users who rely on rsync for large file transfers, as it prevents them from resuming interrupted transfers and instead forces them to restart from scratch.

💡 Why You Are Getting This Error

• The root cause of this error lies in the way the append-verify flag interacts with the partial and inplace options. When these flags are used together, rsync attempts to resume the transfer by appending new data to the existing file, but this can lead to issues when the connection is dropped mid-way. The broken pipe error occurs because rsync is unable to complete the append operation successfully.
• Another possible cause of this error could be related to the way the --no-i-r and --no-perms options interact with the append-verify flag. These options are used to prevent rsync from ignoring file permissions and ownership, but they may also interfere with the append operation, leading to errors.

🚀 How to Resolve This Issue

🎯 Final Words

In summary, disabling the append flags or enabling the partial and inplace options without using the append flags can resolve the issue of rsync crashing upon resuming an interrupted transfer. However, it's essential to weigh the trade-offs between transfer speed and reliability when choosing a solution.