I have set the "File Upload Preferences" set to "all file types", on the grid field i have Allowed file type set to "All". I have the "Channel Form Settings" "Allow Guest Posts" set to yes for that channel.
In the CP i can upload an svg, but not when using exp:channel:form, i can not upload an svg. Using 2.9.3 and need to keep that version for now. I have tried updating the config.php with $config['allowed_types'] = 'svg'; and add to the mimes.php, and nothing lets me upload .svg files from my form (i can upload pngs, jpgs, txt, etc. from that form). Seems to just be svg that gives me "There was a problem with one or more Grid fields".