Error: 'is_latex_output' is not an exported object from 'namespace:knitr' in Rmarkdown

Question

when output the Rmarkdown, there is an error: 'is_latex_output' is not an exported object from 'namespace:knitr'. the Rmarkdown code is very simple:

```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = TRUE)
```
```{r}
print("hello")
```

I use the R version 3.4.4. Rstudio version 1.1.447