Issue

The application deployment failed, and upon reviewing the application logs, the following error was encountered:

Caused by: org.postgresql.util.PSQLException: ERROR: could not create unique index Key (taskid)=(0) is duplicated.

Environment

Applications hosted in Mendix Cloud

Cause

The issue arises due to a unique index constraint on the taskid. When deploying the application, the index creation process fails because multiple rows contain the same taskid value, which is not allowed under a unique index constraint. This typically results from data inconsistencies in the database or a misconfiguration in the domain model. 

Solution/Workaround

To resolve this issue, follow these steps:

1. Clear the database. This ensures the unique index can be created successfully without conflicts during deployment.
2. Recreate the database structure by redeploying the application.
3. Restore a backup

Internal information related

• 239373
• CLDOPS-14443

Additional information 

Mendix Documentation

• Clearing an Environment

• Deploying an App to Mendix Cloud

• Restoring a Backup