We are having troubles at JBoss startup, it's a migration from Appian versio

It seems that you forgot to merge the -override.xml files from <APPIAN_HOME>runtime_ear\\suite.ear\\web.war\\WEB-INF\\conf\\security\\ with the ones from 7.6 and instead you copied them as-is from 7.5. You need to compare your custom file with the ones from 7.6 and merge the customization instead of moving the file directly.

2014-08-25 17:43:12,927 [ServerService Thread Pool -- 70] ERROR org.springframework.web.context.ContextLoader - Context initialization failed
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.security.filterChains': Cannot resolve reference to bean 'org.springframework.security.web.DefaultSecurityFilterChain#28' while setting bean property 'sourceList' with key [28]; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.security.web.DefaultSecurityFilterChain#28': Cannot resolve reference to bean 'mobileClientValidationFilter' while setting constructor argument with key [0];

0. Merge your custom -override.xml files with 7.6
1. Stop JBoss
2. Delete <JBOSS_HOME>\\standalone\\log\\*.log
3. Start JBoss
4. Attach <JBOSS_HOME>\\standalone\\log\\server.log

is this issue resolved?, for me getting same exception with new install 17.3