Please have a look at the following thread which had the same error: UART Bootloader HOST S/W error
Try out the steps mentioned in the above link and let me know if it helps
If not, please attach both the Host Side Visual Studio project and the PSoC Creator project so that we can get more insight on the issue.
Do you know what does it mean?
In this link you can see the bootloader project:
Please download ModusToolbox which comes with the DFU Host Tool. More importantly, you will the latest cybootloaderutils available at this path: "ModusToolbox\tools_2.1\dfuh-tool\sample_code\src\backend\".
Please make use of these files to build your DLL. Also, I went through your PSoC Creator project and I don't see any issues. I did not find the host application code though.