Message type: E = Error
Message class:  UCUM - Messages for Monitor 
Message number: 026
Message text: Task hierarchy contains ambiguous task or task group IDs
The name of a task or task group occurs more than once in the task
hierarchy of your system. This inconsistency must be remedied.
The system issues an error message and will not allow you to continue with this transaction until the error is resolved.
Change the definition of the task hierarchy in the consolidation
workbench. When doing so, delete any duplicate occurrences of the names
of tasks and task groups from the hierarchy. Each name can occur once
only.
Error message extract from SAP system. Copyright SAP SE.
The SAP error message UCUM026, which states "Task hierarchy contains ambiguous task or task group IDs," typically occurs in the context of SAP's Unified Change Management (UCM) or similar project management functionalities. This error indicates that there are duplicate or conflicting task or task group IDs within the task hierarchy, which can lead to confusion in task assignment and tracking.
Cause: Duplicate IDs: The most common cause is that there are two or more tasks or task groups with the same ID in the hierarchy. Incorrect Hierarchy Structure: The structure of the task hierarchy may not be properly defined, leading to ambiguity in task identification. Data Migration Issues: If data has been migrated from another system or if there have been recent changes to the task structure, it may have introduced duplicates or conflicts. Manual Entry Errors: Users may have manually created tasks or groups with the same identifiers without realizing it.
Solution: Identify Duplicates: Use transaction
 Get instant SAP help. Sign up for our Free Essentials Plan.
Get instant SAP help. Sign up for our Free Essentials Plan. 
UCUM025 Value &1 for characteristic &2 is not defined
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
UCUM024 Task &1 has not been created in consolidation area &2
What causes this issue?  Task &V1& has not been created in consolidation area &V2&. Therefore, &V1& cannot be entered as a cut...
UCUM027 Complete all required fields
What causes this issue?  You have not made entries in all required fields.System Response  The system issues an error message and will not allow you t...
UCUM028 Value combination &1 is not valid
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
Click on this link to search all SAP messages.