Not able fetch column name of sharepoint library

Hello All,

I am using sharepoint online modern site. I have build one console application using CSOM.

I able fetch custom column value in code but existing column values not able to fetch in code .

 I have TEST document library . I have added document i want to fetch file name in code but i am getting following error. I have created column country and added value at the time document upload .i am able to fetch name of this column .issue with Name column

Please  help me.

Regards,

Navnath Namde