[Xperia Z1 Compact Q&A, Help & Troubleshooting] OldBeurt:
Thanks for your input !

I don't know where the error came from, but I tried several times (about 10) and it end up the same way ! I will try on another machine (Linux too).

Yes I'm using install.sh, I just pasted the relevat part of the output, but here I paste all of it:

Will attempt to get root to install!
* daemon not running. starting it now on port 5037 *
* daemon started successfully *

=============================================
Step1 : Waiting for Device.
=============================================

Succes

=============================================
Step2 : Sending the recovery files.
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mkdir failed for /data/local/tmp/recovery, File exists
0 KB/s (29 bytes in 0.056s)
362 KB/s (17768 bytes in 0.047s)
325 KB/s (15578 bytes in 0.046s)
11 KB/s (501 bytes in 0.043s)
272 KB/s (11791 bytes in 0.042s)
3186 KB/s (44383 bytes in 0.013s)
70 KB/s (3082 bytes in 0.042s)
9 KB/s (385 bytes in 0.041s)
3645 KB/s (657704 bytes in 0.176s)
3521 KB/s (2597754 bytes in 0.720s)
3936 KB/s (1842873 bytes in 0.457s)
5217 KB/s (2447499 bytes in 0.458s)
193 KB/s (8124 bytes in 0.041s)

=============================================
Step3 : Setup of dual recovery.
=============================================

=============================================
Attempting to get root access for installation using rootkitXperia now.

NOTE: this only works on certain ROM/Kernel versions!

If it fails, please check the development thread on XDA for more details.
=============================================
ro.build.product=C6903
ro.build.id=14.1.G.1.534
search kallsyms...
1 2 3 4
(kallsyms_addresses=c0899410)
(kallsyms_num_syms=00014df1)
kernel dump...
1 2 3 4 5 6 7 8 9

prepare_kernel_cred=c00b89f4
commit_creds=c00b8518
ptmx_fops=c0ea365c

Succeeded in getroot!

##########################################################
#
# Installing XZDR version 2.7.117 BETA
#
#####

Temporarily disabling the RIC service, remount rootfs and /system writable to allow installation.
Copy recovery files to system.
Copy mr wrapper script to system.
Copy chargemon script to system.
Copy dualrecovery.sh to system.
Copy rickiller.sh to system.
Installing NDRUtils to system.
Copy busybox to system.
Trying to find and update the gpio-keys event node.
Found and will be using /dev/input/event4!
Trying to find and update the power key event node.
Found and will be monitoring /dev/input/event3!
Speeding up backups.
Make sure firstboot goes to recovery.

=============================================
DEVICE WILL NOW REBOOT!
=============================================

Error type 2
android.util.AndroidException: Can't connect to activity manager; is the system running?
at com.android.commands.am.Am.run(Am.java:101)
at com.android.commands.am.Am.main(Am.java:82)
at com.android.internal.os.RuntimeInit.nativeFinishInit(Native Method)
at com.android.internal.os.RuntimeInit.main(RuntimeInit.java:235)
at dalvik.system.NativeStart.main(Native Method)
=============================================

REMEMBER THIS:

XZDualRecovery does NOT install any superuser app!!

You can use one of the recoveries to root your device.

=============================================
Waiting for your device to reconnect.
After entering CWM for the first time, reboot to system to complete this installer if you want it to clean up after itself.

=============================================
Installation finished. Enjoy the recoveries!
=============================================