Classic UI not accessible after application migration

Products

• Clarity PPM SaaS
• Clarity PPM On Premise

Issue/Introduction

An old server exists where Clarity is deployed. A new server is provisioned. Content from the old server are migrated into the new server. It is not possible to use the Classic UI after this. Navigating and working in the Modern UX works without any issues. Following error is logged in the app-system.log.

Error:

1857/04/07 12:00:03.899 | java.lang.AbstractMethodError: Receiver class org.restlet.ext.jaxrs.internal.core.ResponseBuilderImpl does not define or inherit an implementation of the resolved method 'abstract javax.ws.rs.core.Response$ResponseBuilder status(int, java.lang.String)' of abstract class javax.ws.rs.core.Response$ResponseBuilder.
1857/04/07 12:00:03.899 |     at javax.ws.rs.core.Response$ResponseBuilder.status(Response.java:921)

Resolution

Rebuild the Clarity folder structure.