[Q] [Flashtool]ERROR - Processing of loader.sin finished with errors.

So I'm trying to downgrade my phone from 5.1.1 to be able to root it.
I have the right ftf file, have all the drivers installed and have the latest flashtool version.
Now when I run Flashtool I get right up to the part where I have to turn off my phone and start it in flashmode.
As soon as I reconnect my phone in flashmode the process aborts and i get this error:
ERROR - Processing of loader.sin finished with errors.

any idea what this means?
Here is the complete log:

Code:

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09/021/2015 23:21:12 - INFO  - Flashtool Version 0.9.19.10 built on 04-10-2015 21:00:00
09/021/2015 23:21:12 - INFO  - Executing search strategies to find proxy selector
09/021/2015 23:21:12 - INFO  - No proxy found for IE. Trying next one
09/021/2015 23:21:12 - INFO  - No proxy found for firefox. Trying next one
09/021/2015 23:21:12 - INFO  - No proxy found for java. Trying next one
09/021/2015 23:21:12 - INFO  - Syncing devices from github
09/021/2015 23:21:12 - INFO  - Scanning devices folder for changes.
09/021/2015 23:21:16 - INFO  - Pulling changes from github.
09/021/2015 23:21:17 - INFO  - Devices sync finished.
09/021/2015 23:21:21 - INFO  - Device disconnected
09/022/2015 23:22:30 - INFO  - Device connected with USB debugging off
09/022/2015 23:22:30 - INFO  - For 2011 devices line, be sure you are not in MTP mode
09/022/2015 23:22:31 - INFO  - Device connected with USB debugging on
09/022/2015 23:22:31 - INFO  - Connected device : Sony Xperia Z2
09/022/2015 23:22:31 - INFO  - Installed version of busybox : N/A
09/022/2015 23:22:31 - INFO  - Android version : 5.1.1 / kernel version : 3.4.0-perf-geae0c9e / Build number : 23.4.A.1.200
09/022/2015 23:22:36 - INFO  - Selected Bundle for Sony Xperia Z2 (D6503). FW release : 23.0.1.A.0.167. Customization : Customized DE
09/022/2015 23:22:36 - INFO  - Preparing files for flashing
09/023/2015 23:23:28 - INFO  - Please connect your device into flashmode.
09/023/2015 23:23:36 - INFO  - Device disconnected
09/023/2015 23:23:46 - INFO  - Device connected in flash mode
09/023/2015 23:23:46 - INFO  - Opening device for R/W
09/023/2015 23:23:46 - INFO  - Start Flashing
09/023/2015 23:23:46 - INFO  - Processing loader.sin
09/023/2015 23:23:46 - INFO  -    Checking header
09/023/2015 23:23:46 - ERROR - Processing of loader.sin finished with errors.
09/023/2015 23:23:46 - INFO  - Ending flash session
09/023/2015 23:23:46 - ERROR -
09/023/2015 23:23:46 - ERROR - Error flashing. Aborted
09/023/2015 23:23:47 - INFO  - Device connected in flash mode

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