Python incompatibility(?) Rhino5 vs. Rhino6

I am new in Python programming.
My first program was tested in Rhino5, and worked well.
In Rhino6 I get an error message for the sam program, and same parameters.

Could any of you give an explanation, and a solution for the following problem ?

A Python script is running well in Rhino5, but in Rhino6 fails.

The problem coused by the following command:

    rs.Command("_-Import %s %s _Enter" % (iPath, mUnit))

where :slight_smile:

iPath = A:\2018\Gyártás\Értékesítés\P17143I1-DM21_EGIS 25.épület\CNC\2018.03.07\D311-7.dwg

in the Rhino 6 commandline the file extension is changet to .3dm with an error message:

File A:\2018\Gyártás\Értékesítés\P17143I1-DM21_EGIS.3dm not found, unable to open

Why Rhino6 changes the file extension, and how to avoid this?

Why is this difference between the two system, and how to solve it?