Symptoms

Configuring a trusted communication application between JIRA and a cloned Confluence instance failed due to this error message, thrown by JIRA:

The Trusted Application with the specified applicationId: confluence:14749191 already exists

Cause

Each of the trusted application configurations requires a unique application ID. In this case, the original application ID (14749191) owned by the production instance is associated to the cloned instance, too. JIRA is unable to proceed due to this clash.

Resolution

Please follow the steps outlined in How to create a cloned Confluence instance with a new server ID and application ID to generate a new unique application ID.