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 : [""][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