Path Analyzer related errors in the log after upgrading Sitecore XP


Description

Personalization rules might fail with Path Analyzer related exceptions after upgrading Sitecore XP to 9.0 Initial Release or higher. The root cause of the issue are obsolete rules items under /sitecore/system/Settings/Rules/Definitions/Elements/Visit/*. Starting from Sitecore XP 9.0, Experience Analytics uses the new segmentation rules that a user creates by themselves instead of the rule items. For example, the rule /sitecore/system/Settings/Rules/Definitions/Elements/Visit/Visit language was replaced by the segment /sitecore/system/Marketing Control Panel/Experience Analytics/Dimensions/Visits/By language/All visits by language. The following message can be found in the log records:

ERROR [Path Analyzer] Error during aggregation.
Exception: Sitecore.XConnect.Segmentation.ExpressionBuilder.PredicateDescriptorException
Message: No known predicate type could be determined from 'Sitecore.ExperienceAnalytics.Aggregation.Rules.Conditions.VisitLanguageCondition,Sitecore.ExperienceAnalytics' specified in the definition item (Id = 'dceaf329-d74d-42e5-9023-452e08cde246', db = 'master') : Could not load type 'Sitecore.ExperienceAnalytics.Aggregation.Rules.Conditions.VisitLanguageCondition' from assembly 'Sitecore.ExperienceAnalytics'.
Source: Sitecore.Marketing.Segmentation.xMgmt
   at Sitecore.Marketing.Segmentation.ExpressionBuilder.ContentTreePredicateDescriptorLocator.GetDescriptor(Guid id)
   at Sitecore.Marketing.Segmentation.RuleXmlConverter.ConditionXmlNodeConverter.LookupType(Guid descriptorId)
...

Solution

To resolve the issue, remove the following rules items: