Hello David,
The best way to customize these pages is to use Template File Scripting :
https://www.ibm.com/support/knowledgecenter/en/SSPREK_9.0.7/com.ibm.isam.doc/config/reference/template_file_scripting_aac.htmlSince the error message is held in a macro, you can either hard code the response in the template file or you can perform conditional logic to vary your response depending on the error code.
The page in question should be the 'C/authsvc/server_error.html' I believe.
You can access these pages at 'Secure Access Control -> Global Settings -> Template Files' from your Appliance LMI.
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JACK YARBOROUGH
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