Why Pandoc does not retrieve the image file?

Question

On RStudio version 0.98.501 I had a long .Rmd file which was easily converted to html once I clicked KnitHtml button. The Knitting process, as I understand, created several folders including images (some manually added by myself), figures, cache and a knitHtml folder which included final .html file. I recently downloaded RStudio version 0.98.894 (preview release) because I wanted to use more features. Now, when I click KnitHtml I get following error:

pandoc.exe: Failed to retrieve C:/Users/durraniu/Documents/Trajectory1/images/vissim-view.png InvalidUrlException "C:/Users/durraniu/Documents/Trajectory1/images/vissim-view.png" "Invalid scheme" Error: pandoc document conversion failed with error 61

I copied all the images including the vissim-view.png as indicated above, from the images folder to the knitHtml folder and clicked the button again. This time it gave the same error related to image file which R would create i.e a plot. How to resolve this?

Answer 1

While there are multiple correct solutions above, I'd like to add that a common cause of this error is syntactical, when the author accidentally wraps the file name in the markdown in quotes:

![my image]("my_image.png")

This will result in pandoc being unable to locate the file. I find this mistake to be easy to make in knitr, since we are intertwining R scripts with markdown.

The correct way to insert the image is:

![my image](my_image.png)

Answer 2

I encountered a similar error like this: pandoc.exe: Could not find data file ProjectPart1_files/figure-html/sample_Mean_versus_Theoretical_Mean-1.png Error: pandoc document conversion failed with error 97

And one sentence from this page solved my problem.

"If you run into problems with cached output you can always clear the knitr cache by removing the folder named with a _cache suffix within your document’s directory."

When the error occurred, there exactly existed a folder with name like "ProjectPart1_cache" in the working directory. After I deleted it, the error was removed.