API error message that can be used for client side localisation of API errors.
- $1 is the extension(s) of the file which cannot be uploaded
- $2 is the list of file extensions that can be uploaded (Example: png, gif, jpg, jpeg, ogg, pdf, svg.)
- $3 is the number of allowed file formats (to be used for the PLURAL function)
- $4 is the number of extensions that could not be uploaded (to be used for the PLURAL function)