Error in running Iso-Area polygon algorithm of QNEAT3 plugin

I am going to generate isochrones using Iso-Area algorithm of QNEAT3 plugin. I have a CSV file including start point coordinates. I read this file as a layer in QGIS. Then I saved the features of this layer (Let’s consider it A) as it is shown in the next picture:

I also downloaded the road network from http://download.geofabrik.de/ and added it as a layer to QGIS. Then I saved this layer (Let’s consider it B) as it is shown in the following figure:

Finally in the Iso-Area as polygon (from layer) parameters tab, I selected B as the input of vector layer representing network and A as the input of stat points. after running the algorithm I got this error:

there is not any clear message regarding the error happened. what could be a probable cause of this problem?