[ChunkedOutputStream.FlushData.execute Failed to flush buffer to this destination


[ChunkedOutputStream.FlushData.execute Failed to flush buffer to this destination Error=com.ahsay.afc.cloud.d Failed to get OutputStream of file" (5231)


When running a backup job on AhsayOBM/AhsayACB the following error is shown in the backup log:


This issue is caused by an unstable network connection between the device backing up and the backup destination, or limited bandwidth.


Firstly, and if you are using our Pro service, check your server’s connection to the Microsoft cloud [Azure] we use in the UK. This link will take you to our speed test server on Azure.
We store all Pro data on Azure in the UK.

If you are using our Your Storage service, or an Azure region outside of the UK, you should use the standard test service provided by your ISP or www.speedtest.net


Fine tune the timeout and retry parameters to workaround the unstable network connection issue by increasing the number of retry and or read timeout values. This can be done by editing the %BOBCLOUD_INSTALL%\afc.opt file

Parameter Description

The number of times the backup should retry to send a block to the backup destination. The default value for retries is 10 times.

The read timeout interval before the backup retries sending a block to the backup destination. The default timeout value is 90 minutes.

The default maximum sleep interval value is 16 minutes, i.e. if the data block upload fails, then AhsayOBM/AhsayACB will sleep for (30 sec) x 2^(no. of retry - 1) minutes and then retry to upload the data block again, which the maximum sleeping interval is 16 minutes (960 seconds), i.e 30 sec, 60 sec, 120 sec, 240 sec, 480 sec, 960 sec, 960 sec, 960 sec, 960 sec, 960 sec…

Add the following values to the afc.opt file.

Recommended values:

Save the file
Run the backup job again.

Retry, timeout, network, sleep, network, ChunkedOutputStream.FlushData