Issue Summary

When a Jira Data Center app uses the App Migration Platform's Forge Object Store path to upload migration data directly from DC to Forge storage during the onMigrationStarted event, the operation fails for Forge apps installed on sites in the EU region. The Forge Object Store path is not functioning as expected in the EU region, making the migration pathway unavailable for EU-region customers.

This affects any vendor implementing DC-to-Forge custom field or data migration that relies on the AppCloudForgeMigrationGateway to write to Forge Object Store as part of the migration flow.

Steps to Reproduce

1. Implement DiscoverableForgeListener on a DC app with an onMigrationStarted handler that writes to Forge Object Store via AppCloudForgeMigrationGateway.
2. Deploy the Forge counterpart app and install it on a Jira Cloud site in the EU region.
3. Trigger a DC-to-Forge migration via JCMA.
4. In the onMigrationStarted Forge trigger, attempt to write or retrieve data via the Forge Object Store migration path.
5. Observe the failure.

Expected Results

The Forge Object Store migration path works consistently across all supported Atlassian Cloud regions, including EU.

Actual Results

The migration fails when the destination site is in the EU region. The Forge Object Store path is not available or not functioning correctly for EU-region sites, blocking the entire migration for any app that relies on this mechanism. Vendors and their customers in the EU region have no viable alternative path to complete the migration.

Workaround

Currently there is no known workaround for this behavior. A workaround will be added here when available.