CM 9.3 handling special character for file name

Our customer is trying to extract a file that the file name include “%” or “ ” symbol using SDK extractDocument.DoExtract(extractDocumentDirectory, overwriteOk, checkoutDocument, rootUrlForHyperLinks);

The SDK flows the error “The file name contains invalid characters.”

Is there a way to use the SDK with “%” or “ ” ?

Anyone had the same experience can share please?