We have migrated Appian instance from 7.3 to 7.5 + Hotfix D . During the post va

Actually what happened is what is documented here: forum.appian.com/.../Appian_Release_Notes under issue AN-42289:

"Attempting to invoke a rule with an incorrect domain, such as ruel!myRule() instead of `rule!myRule(), now causes an error. Previously, no error was thrown, but any dependencies caused by this invocation would not be discovered during export."

So basically someone by mistake was typing torule! in 7.3 for those expressions. This used to work since the domain before ! for execution of rules used to be simply ignored. Since this was causing the dependencies not to be found when exporting this was fixed and the domain or prefix before the ! is now taken into consideration, that's why this typo now matters and in 7.5 it will error out which is what is making you notice it.

Actually what happened is what is documented here: forum.appian.com/.../Appian_Release_Notes under issue AN-42289:

"Attempting to invoke a rule with an incorrect domain, such as ruel!myRule() instead of `rule!myRule(), now causes an error. Previously, no error was thrown, but any dependencies caused by this invocation would not be discovered during export."

So basically someone by mistake was typing torule! in 7.3 for those expressions. This used to work since the domain before ! for execution of rules used to be simply ignored. Since this was causing the dependencies not to be found when exporting this was fixed and the domain or prefix before the ! is now taken into consideration, that's why this typo now matters and in 7.5 it will error out which is what is making you notice it.