Validate field to allow file upload - files are uploading twice

Could you format this into a reproducible example? That is a set of code or rstudio.cloud project that folks can easily get up and running to replicate your issue? Currently, this is only part of a shiny app.

IF you aren't familiar with best practices for shiny reprexes, check out

This will make it easier for folks to replicate your issue and offer suggestions to solve it.