Question: Is it possible to upgrade from 10.1.x to 10.3.x directly in **one step? or I have to upgrade first to 10.2. x then to 10.3.x.**

Please it is so important question regarding upgrading our production MariaDB servers and I couldn't find any answer or notes regarding upgrade from 10.1 series to 10.3 series.

So i have to do it as follow: 
10.1.32 --> 10.2.16  

10.2.16 --> 10.3.7 
or 
once 10.1.32 --> 10.3.7

Answer: 
Upgrades are only tested from one major version to the next, so you'll have to do 10.1->10.2.

Documentation for each upgrade:

[Upgrading from MariaDB 10.1 to MariaDB 10.2](https://mariadb.com/kb/en/library/upgrading-from-mariadb-101-to-mariadb-102/)

[Upgrading from MariaDB 10.2 to MariaDB 10.3](https://mariadb.com/kb/en/library/upgrading-from-mariadb-102-to-mariadb-103/)
If you must go the direct route, but actual direct upgrading doesn't work, what you can do is: 

1. Install MariaDB 10.3 on a new server
2. Make a logical backup (typically `mysqldump`) of the 10.1 production server
3. Import the backup to the new MariaDB 10.3 production server.