Cannot upload data file to R Studio Server (unexpected response from server)

rstudio

#1

Newly deployed R Studio Server in AWS, I added several local system users. They can log in the R Studio Server, but could not upload the data file. R Studio says "unexpected response from server", I have tried permission to the user. I also added users and "server-user" to the same group, and granted permission to the group. Nothing changed. Can anyone help? ("server-user" setting is in the "rserver.conf" file).
image