Error: Fatal error: cannot create 'R_TempDir'

Has anyone encountered this error?

Error: Fatal error: cannot create 'R_TempDir'

I do need to use the tempdir() and create some files over there. When I use it locally, everything works. When I deployed to shinyapps.io, it worked fine before. However, it suddenly had this error of today. There is no new deployment between it was fine and today's error.

Is it some file system, permission issue?

Thanks in advance.