SAS Logon Manager offers the ability to provide custom content with the sas.logon.custom configuration properties. When you configure these properties in a SAS^® Viya^® 3.5 environment, certain versions of SAS Logon Manager might return an HTTP 500 error.

When this issue occurs, the /opt/sas/viya/config/var/log/saslogon/default/sas-saslogon_<date>.log file contains errors similar to the following:

2026-07-08 14:00:16.664 ERROR 3734310 — [8-auto-1-exec-6] org.thymeleaf.TemplateEngine : service [ab788f9ec27f41eb] [THYMELEAF]https-jsse-nio-10.208.8.198-auto-1-exec-6 Exception processing template "login": Instantiation of new objects and access to static classes or parameters is forbidden in this context (template: "login" - line 69, col 21)

org.thymeleaf.exceptions.TemplateProcessingException: Instantiation of new objects and access to static classes or parameters is forbidden in this context (template: "login" - line 69, col 21)

…

2026-07-08 14:00:16.708 ERROR 3734310 — [8-auto-1-exec-6] org.thymeleaf.TemplateEngine : service [ab788f9ec27f41eb] [THYMELEAF]https-jsse-nio-10.208.8.198-auto-1-exec-6 Exception processing template "error": Exception evaluating SpringEL expression: "#httpServletRequest.getAttribute('sas.error.message') == null" (template: "error" - line 15, col 99)

org.thymeleaf.exceptions.TemplateProcessingException: Exception evaluating SpringEL expression: "#httpServletRequest.getAttribute('sas.error.message') == null" (template: "error" - line 15, col 99)

There is no workaround for this issue.