Which Special Characters allowed for folder names?

Recently we experienced a user uploading files to a folder with special character “#” pre-fixed to it and it caused grief.

We believe the special character is not allowed and most common sense tell most people
to not use a special character by default anyway.

Was just curious, we had the user remove the “#” for folder names and it seemed to have helped.

yeah special character should never be used as prefixes in names it can mess things up as for your question you should assume that every special char is not allowed to prevent being in troubles.