The importfiles element in the ai section of the master controller configuration, has a failed attribute. This can be used to configure the folder relative to the basedir that contains the the failed imports:
<ai>
<importfiles url="ftp://ftp.deltares.nl/files"
basedir="D:/data/"
dumps="DumpFiles" failed="ImportFailed" succeeded="ImportBackup"
archiveexport="Archive/export" archiveimport="Archive/import"/>
If this value is configured, the failed imports page will look as follows.
