Stuck on reinstallation of OS X 10.11.6 El Capitan When I trigger the reinstallation of OS X 10.11.6 El Capitan while in Recovery Mode starting "Reinstall OS X" the InstallAssistant immediately fails:

Mar 16 00:52:25 MacBook-Pro InstallAssistant[458]: @(#)PROGRAM:Install  PROJECT:Install-1000
Mar 16 00:52:25 MacBook-Pro InstallAssistant[458]: @(#)PROGRAM:IA  PROJECT:InstallAssistant-532
Mar 16 00:52:25 MacBook-Pro InstallAssistant[458]: Hardware: MacBookPro12,1 @ 3.10 GHz (x 4), 8192 MB RAM
Mar 16 00:52:25 MacBook-Pro InstallAssistant[458]: Running OS Build: Mac OS X 10.11.6 (15G31)
Mar 16 00:52:25 MacBook-Pro InstallAssistant[458]: Env: DYLD_NO_FIX_PREBINDING=1
Mar 16 00:52:25 MacBook-Pro InstallAssistant[458]: Env: PATH=/usr/bin:/bin:/usr/sbin:/sbin
Mar 16 00:52:25 MacBook-Pro InstallAssistant[458]: Env: PWD=/
Mar 16 00:52:25 MacBook-Pro InstallAssistant[458]: Env: XPC_FLAGS=0x0
Mar 16 00:52:25 MacBook-Pro InstallAssistant[458]: Env: XPC_SERVICE_NAME=0
Mar 16 00:52:25 MacBook-Pro InstallAssistant[458]: Env: SHLVL=1
Mar 16 00:52:25 MacBook-Pro InstallAssistant[458]: Env: __OSINSTALL_ENVIRONMENT=1
Mar 16 00:52:25 MacBook-Pro InstallAssistant[458]: Env: CI_DEFAULT_OPENCL_USAGE=0
Mar 16 00:52:25 MacBook-Pro InstallAssistant[458]: Env: OS_INSTALL=1
Mar 16 00:52:25 MacBook-Pro InstallAssistant[458]: Env: _=/System/Library/CoreServices/Language Chooser.app/Contents/MacOS/Language Chooser
Mar 16 00:52:25 MacBook-Pro InstallAssistant[458]: Can not connect to /var/run/systemkeychaincheck.socket: No such file or directory
Mar 16 00:52:25 MacBook-Pro InstallAssistant[458]: OSInstallChunkedDownload loaded...
Mar 16 00:52:25 MacBook-Pro InstallAssistant[458]: OSInstallChunkedDownload loaded...
Mar 16 00:52:25 MacBook-Pro InstallAssistant[458]: IAPisaDownload loaded...
Mar 16 00:52:25 MacBook-Pro InstallAssistant[458]: IAPisaDownload loaded...
Mar 16 00:52:25 MacBook-Pro Unknown[420]: 2020-03-16 00:52:25.770 InstallAssistant[458:14619] NSColorList could not parse color list file /System/Library/Colors/System.clr
Mar 16 00:52:25 MacBook-Pro Unknown[420]: 2020-03-16 00:52:25.779 InstallAssistant[458:14619] Failed to connect (keyReceivingView) outlet from (IASetupWindowController) to (PUKDiskPickerHorizontalView): missing setter or instance variable


When I look at the above message Can not connect to /var/run/systemkeychaincheck.socket: No such file or directory I guess the issue might be related to the current SIP setting, which is "enabeled".

Question
 Should I rerun the job with SIP switched off? Any advice how to overcome this issue is highly welcome.

Hardware-Software-Environment

MacBook Pro Early 2015 running OS X 10.11.6 El Capitan.
The internal HD is actually a 250 GB SSD comprising partitions EFI, Macintosh HD and Recovery HD. There is no encryption enabled on any of these partitions.
The processing steps sketched below fixed the issue.

Hardware-Software-Environment

MacBook Pro Early 2015 running OS X 10.11.6 El Capitan.
The internal HD is actually a 250 GB SSD comprising partitions EFI, Macintosh HD and Recovery HD. There is no encryption enabled on any of these partitions.
 At the time we started the reinstallation attempt described here, the Macintosh HD partition is unusable as startup volume due to a previously stuck installation attempt, see question above.  

Processing Steps  


We boot the machine from a startup volume residing on an external HD connected via USB 3.0 Bus. Then we log in to a session in Normal Mode under OS X 10.11.6 .  
We download a new El Capitan installation package from 
http://updates-http.cdn-apple.com/2019/cert/061-41424-20191024-218af9ec-cf50-4516-9011-228c78eda3d2/InstallMacOSX.dmg  
We unpack the package to install the macOS installer.  
Now we just run the installer; Internet connection off. The machine rebooted and, after approximately 30 minutes, reappeared with a login screen.  
We could verify that OS X 10.11.6 BuildVersion 15G31 had been properly reinstalled to the Macintosh HD partition with no user data or previously installed third party software lost.  


Reference
How to upgrade to OS X El Capitan

Acknowledgement
Thanks a lot to @Udhy for the decisive hint to fix the issue.