Flexisip error Failed to find shared library for backend mysql

I installed Flexisip using official documentation , installed additional components like MariaDB (MySQL) and Redis, performed initial setup of configuration files, created database and DB user.

I started flexisip services with

and by looking in /var/opt/belledonne-communications/log/flexisip/flexisip-conference.log I noticed the following error:

What I tried:

1) Installed libsoci-mysql3.2 package:

(there is no libsoci-mysql4.0 package available for Debian 9 at the moment)
2) Restarted flexisip-conference service and got the same error
3) ~ 3 hours of digging in /usr/lib/ ,  checked each and every library dependency, made soft links like

and so on but nothing helped
4) Launched

and found the following line:

FlexiSip comes bundled with Libsoci core library (libsoci_core.so.4.0) but without backend libraries and libsoci_core.so.4.0 looks for backend extensions libsoci_{backend}.so.{version} at the same path where it resides!
5) Copied :

and renamed:

6) Restarted Flexisip conference:

7) Checked the log (debug level enabled already):

The error is gone!

Check my guide on Flexisip installation and configuration on Debian 9 !

Good luck!