[Xperia SP Q&A, Help & Troubleshooting] xperia.sp.lbl.rr:
And again:

10/053/2015 20:53:49 - INFO - Flashtool Version 0.9.18.6 built on 30-05-2015 22:30:00

10/053/2015 20:53:49 - INFO - Executing search strategies to find proxy selector

10/053/2015 20:53:50 - INFO - No proxy found for IE. Trying next one

10/053/2015 20:53:50 - INFO - No proxy found for firefox. Trying next one

10/053/2015 20:53:50 - INFO - No proxy found for java. Trying next one

10/053/2015 20:53:50 - INFO - Syncing devices from github

10/053/2015 20:53:52 - INFO - Scanning devices folder for changes.

10/054/2015 20:54:10 - INFO - Pulling changes from github.

10/054/2015 20:54:14 - INFO - Devices sync finished.

10/054/2015 20:54:19 - INFO - Device disconnected

10/057/2015 20:57:59 - INFO - Selected Bundle for Sony Xperia SP (C5303). FW release : 12.1.A.1.207. Customization : AU

10/057/2015 20:57:59 - INFO - Preparing files for flashing

10/058/2015 20:58:21 - INFO - Device connected with USB debugging off

10/058/2015 20:58:21 - INFO - For 2011 devices line, be sure you are not in MTP mode

10/059/2015 20:59:11 - INFO - Selected Bundle for Sony Xperia SP (C5303). FW release : 12.1.A.1.207. Customization : AU

10/059/2015 20:59:11 - INFO - Preparing files for flashing

10/059/2015 20:59:12 - ERROR - Cannot delete C:\Users\Rhubarb\.flashTool\firmwares\prepared\system.sin

10/059/2015 20:59:12 - INFO - Cannot open bundle. Flash operation canceled

10/059/2015 20:59:21 - INFO - Selected Bundle for Sony Xperia SP (C5303). FW release : 12.1.A.1.207. Customization : AU

10/059/2015 20:59:21 - INFO - Preparing files for flashing

10/059/2015 20:59:21 - ERROR - Cannot delete C:\Users\Rhubarb\.flashTool\firmwares\prepared\system.sin

10/059/2015 20:59:22 - INFO - Cannot open bundle. Flash operation canceled

10/000/2015 21:00:26 - INFO - Selected Bundle for Sony Xperia SP (C5303). FW release : 12.1.A.1.207. Customization : AU

10/000/2015 21:00:26 - INFO - Preparing files for flashing

10/000/2015 21:00:26 - ERROR - Cannot delete C:\Users\Rhubarb\.flashTool\firmwares\prepared\system.sin

10/000/2015 21:00:26 - INFO - Cannot open bundle. Flash operation canceled

10/000/2015 21:00:33 - INFO - Flash canceled

10/000/2015 21:00:48 - INFO - Selected Bundle for Sony Xperia SP (C5303). FW release : 12.1.A.1.207. Customization : AU

10/000/2015 21:00:48 - INFO - Preparing files for flashing

10/000/2015 21:00:48 - ERROR - Cannot delete C:\Users\Rhubarb\.flashTool\firmwares\prepared\system.sin

10/000/2015 21:00:48 - INFO - Cannot open bundle. Flash operation canceled

10/001/2015 21:01:00 - INFO - Device disconnected

10/001/2015 21:01:17 - INFO - Device connected with USB debugging off

10/001/2015 21:01:17 - INFO - For 2011 devices line, be sure you are not in MTP mode

10/001/2015 21:01:19 - INFO - Device disconnected

10/001/2015 21:01:42 - INFO - Please connect your device into flashmode.

10/002/2015 21:02:08 - INFO - Device connected with USB debugging off

10/002/2015 21:02:08 - INFO - For 2011 devices line, be sure you are not in MTP mode

10/002/2015 21:02:13 - INFO - Device disconnected

10/005/2015 21:05:35 - INFO - Flash canceled

10/005/2015 21:05:48 - INFO - Selected Bundle for Sony Xperia SP (C5303). FW release : 12.1.A.1.207. Customization : AU

10/005/2015 21:05:48 - INFO - Preparing files for flashing

10/008/2015 21:08:12 - INFO - Please connect your device into flashmode.

10/012/2015 21:12:48 - INFO - Device connected in flash mode

10/012/2015 21:12:49 - INFO - Opening device for R/W

10/012/2015 21:12:49 - INFO - Reading device information

10/012/2015 21:12:49 - INFO - Phone ready for flashmode operations.

10/012/2015 21:12:49 - INFO - Current device : C5303 - CB512456FU - 1272-3352_R1B - 1272-3352_12.1.A.1.207 - GLOBAL-LTE_12.1.A.1.207

10/012/2015 21:12:49 - INFO - Start Flashing

10/012/2015 21:12:49 - INFO - Processing loader.sin

10/012/2015 21:12:49 - INFO - Checking header

10/012/2015 21:12:49 - INFO - Flashing data

10/012/2015 21:12:49 - INFO - Processing of loader.sin finished.

10/012/2015 21:12:53 - INFO - Loader : S1_Root_7054 - Version : R5G006 / Boot version : R11B023 / Bootloader status : NOT_ROOTABLE

10/012/2015 21:12:53 - INFO - Processing partition-image.sin

10/012/2015 21:12:53 - INFO - Checking header

10/012/2015 21:12:53 - INFO - Flashing data

10/012/2015 21:12:53 - INFO - Processing of partition-image.sin finished.

10/012/2015 21:12:53 - INFO - No bootdelivery to send

10/012/2015 21:12:54 - INFO - Processing kernel.sin

10/012/2015 21:12:54 - INFO - Checking header

10/012/2015 21:12:54 - INFO - Flashing data

10/012/2015 21:12:56 - INFO - Processing of kernel.sin finished.

10/012/2015 21:12:56 - INFO - Processing fotakernel.sin

10/012/2015 21:12:56 - INFO - Checking header

10/012/2015 21:12:56 - INFO - Flashing data

10/012/2015 21:12:58 - INFO - Processing of fotakernel.sin finished.

10/012/2015 21:12:58 - INFO - Processing amss_fs_2.sin

10/012/2015 21:12:58 - INFO - Checking header

10/012/2015 21:12:59 - INFO - Flashing data

10/012/2015 21:12:59 - INFO - Processing of amss_fs_2.sin finished.

10/012/2015 21:12:59 - INFO - Processing amss_fs_1.sin

10/012/2015 21:12:59 - INFO - Checking header

10/012/2015 21:12:59 - INFO - Flashing data

10/012/2015 21:12:59 - INFO - Processing of amss_fs_1.sin finished.

10/012/2015 21:12:59 - INFO - Processing amss_fsg.sin

10/012/2015 21:12:59 - INFO - Checking header

10/012/2015 21:12:59 - INFO - Flashing data

10/012/2015 21:12:59 - INFO - Processing of amss_fsg.sin finished.

10/012/2015 21:12:59 - INFO - Processing apps_log.sin

10/012/2015 21:12:59 - INFO - Checking header

10/012/2015 21:12:59 - INFO - Flashing data

10/013/2015 21:13:00 - INFO - Processing of apps_log.sin finished.

10/013/2015 21:13:00 - INFO - Processing cache.sin

10/013/2015 21:13:00 - INFO - Checking header

10/013/2015 21:13:00 - INFO - Flashing data

10/013/2015 21:13:03 - INFO - Processing of cache.sin finished.

10/013/2015 21:13:03 - INFO - Processing system.sin

10/013/2015 21:13:03 - INFO - Checking header

10/013/2015 21:13:03 - INFO - Flashing data

10/016/2015 21:16:23 - ERROR - Processing of system.sin finished with errors.

10/016/2015 21:16:23 - INFO - Ending flash session

10/016/2015 21:16:23 - ERROR - Read error :2 : Le fichier spécifié est introuvable.

10/016/2015 21:16:23 - ERROR - Error flashing. Aborted

10/016/2015 21:16:24 - INFO - Device disconnected

10/016/2015 21:16:24 - INFO - Device connected with USB debugging off

10/016/2015 21:16:24 - INFO - For 2011 devices line, be sure you are not in MTP mode

10/016/2015 21:16:29 - INFO - Device disconnected