openBinaryFile: does not exist (No such file or directory)

After doing the above mentioned, I am not able to knit my document.

I'm actually trying to create multiple pdfs like in the code mentioned here : ["https://stackoverflow.com/questions/38572219/how-to-create-a-different-report-for-each-subset-of-a-data-frame-with-r-markdown/38572516#38572516"][1]

But getting the error every time :

Error: pandoc document conversion failed with error 1

In addition: Warning messages:
1: In yaml::yaml.load(yaml, handlers = knit_params_handlers(evaluate = evaluate), :
an error occurred when handling type 'r'; using default handler
2: In dml$SUBJECTNUMBERSTR == params$Subject :
longer object length is not a multiple of shorter object length