Error when trying to import GTF files using rtracklayer’s import function

I’m trying to use rtracklayer’s import function to import a GTF file. I downloaded the current comprehensive genome annotation for human from GENCODE, gunzipped the .gz file and tried the following:

library(rtracklayer)
granges <-import("gencode.v36.annotation.gtf")

I am getting the following error:

Error in h(simpleError(msg, call)) : 
  error in evaluating the argument 'con' in selecting a method for function 'import': invalid class “GFF2File” object: undefined class for slot "resource" ("characterORconnection")

Also, adding the parameter format="gtf" does not make a difference.

When searching for this on the web, I’m only getting results regarding a tool called IsoformSwitchAnalyzeR where the authors recommended updating their software. But I’m neither using their tool, nor is it even installed on my PC.

For now, I am importing the GTF files manually, but I would like to use rtracklayer’s import function. I hope, someone can help.