Webdynpro Java application: 500 internal server error

Hello SAP Experts,

While clicking the dropdown (combo box) elements in a WebDynrpo Java application, a '500 internal server error' is thrown.

I have attached screenshots of the error:

The following log in the defaultTrace files shows a exception similar to the following:

500 Internal Server Error is returned for HTTP request [...]:
component [dispatcher],
web module [...],
application [...],
DC name [...],
CSN component[BC-WD-JAV],
problem categorization [],
internal categorization [-1671306692].

[EXCEPTION]
com.sap.tc.webdynpro.services.exceptions.WDRuntimeException

Caused by: java.lang.NumberFormatException: For input string: 'aaabLEOANGCMKHAJ.DefineCriteriaView.SearchDefinitions.SearchableObjectType.ObjectTypeTitle'

The error can be re-generated by following:

• First access any WebDynpro Java application, standalone or within the Enterprise Portal ex. http(s)://<host>:<port>/useradmin
• Now click any dropdown element
• An error '500 internal server error' is shown.