Invoke api giving follwoing error

{“ParsedResults”:[],“OCRExitCode”:99,“IsErroredOnProcessing”:true,“ErrorMessage”:[“Unable to process the file. Please check if the file has sufficient permissions and allows access and is not corrupt.”],“ProcessingTimeInMilliseconds”:“343”,“SearchablePDFURL”:""}

https://api.ocr.space/parse/imageurl?apikey=helloworld&url=C:\Users\sk12t\Downloads\R4&filetype=pdf
This is what I am trying

C:\Users\sk12t\Downloads\R4 is not a URL to a PDF, that is why you get this error.

This works ok:

https://api.ocr.space/parse/imageurl?apikey=helloworld&url=https://file-examples.com/wp-content/uploads/2017/10/file-sample_150kB.pdf&filetype=pdf

If you want to upload a file from your hard drive, you can not use the GET method, but you must use the POST method, e. g. with the CURL tool:

https://ocr.space/ocrapi#curl