For the path you are using, the Rmd file should be in the root folder of your app (the same where the app.R file is located).
Doing this, especially on a Shiny app is a bad idea, the app is going to fail on deployment.
A better workflow would be to create a project for your app, that way you don't need to manually set the working directory.
This simple example works for me
library(shiny)
library(markdown)
ui = fluidPage(
textInput("year", "Enter Year"),
downloadButton("report", "Generate report")
)
server <- function(input, output, session) {
output$report <- downloadHandler(
filename = "report.html",
content = function(file) {
params <- list(year = input$year)
rmarkdown::render("report.Rmd",
output_file = file,
params = params,
envir = new.env(parent = globalenv())
)
}
)
}
shinyApp(ui, server)
report.Rmd
---
title: "Test"
output: html_document
params:
year: "2020"
---
```{r}
params$year
```
Rendered report
