KB-1789 "A side by side layout has an invalid item." error when accessing applications and objects in /design


Following a site upgrade or restart, users receive the following error when attempting to access an application or object in /design:


The following error is observed in the application server log:

ERROR com.appiancorp.rest.shared.AppianExceptionMapper - Internal Server Error on REST API invocation.
com.appiancorp.exceptions.LocalizedAppianRuntimeException$LocalizedAppianException: Expression evaluation error : A side by side layout has an invalid item. The item at index 2 contains a component that is not supported in a side by side layout. Received: <X>.


This issue is related to the way that the application server caches Appian system rules. This issue has been reported to the Appian Product Team. The reference number for this issue is AN-119114


Restart the application server.

If the environment has multiple application servers, it is only necessary to restart the application server that is experiencing the issue. To identify the the application server that is experiencing the issue, refer to the instructions outlined in KB-1442.

Affected Versions

This article applies to all versions of Appian.

Last Reviewed: November 2018