CDC Database Migration Job failing after full dump via PSC

Google Cloud Database
1

Hello!

We need to perform a cross-project migration of a MySQL database running on GCE to Cloud SQL.
Following the docs I created a network attachment in the source project, in the target project I’ve created a new instance instance and configured PSC-outbound connectivity → Connect to an instance using Private Service Connect  |  Cloud SQL for PostgreSQL  |  Google Cloud Documentation

Job started and full dump phase was done, however when the CDC replication was about to start the job stated to fail with timeout error, looks like the replica cannot connect to the source anymore.

What is the expected behavior here? Is the PSC connection working onyl for one-time migration? Does CDC work via PSC? Seems like after full dump the instance got restarted and disconnected from the network attachment.

2

Hi Cristian, the PSC connection should work for the migration for all phases (full dump + CDC). The support is dependent on the destination, it sounds like the CSQL instance had an issue and aborted the migration. There are additional considerations on the public documentation, lease review Configure private IP connectivity  |  Database Migration Service for MySQL  |  Google Cloud Documentation and if it doesn’t help you can open a bug and we could take a deeper look.

1 Like
3

Hi Adi, thanks for the reply!
Our source MySQL instance runs on GCE in project A, we want to migrate it to Cloud SQL in project B. There’s peering between the 2 projects (replication works via proxy VM). I’ve created a new Cloud SQL MySQL instance and configured PSC with outbound connectivity (PSA disabled).
When starting the migration job, connection works and starts the full dump, however at some point if fails and the error about timeout is showing some internal IP (I guess DMS worker).

Error connecting to source '<username>@169.254.0.2:3306'. This was attempt 1/10, with a delay of 60 seconds between attempts. Message: Can't connect to MySQL server on '169.254.0.2:3306' (110),

Migration job logs:

Destination instance logs:
INFO 2026-03-19T15:30:41.654516Z Connection to source database server established.
INFO 2026-03-19T15:32:35.755229Z Connection to source database server established.
INFO 2026-03-19T15:32:37.642655Z Connection to source database server established.
INFO 2026-03-19T15:34:13.117513Z DUMP_STAGE(START): Start importing data from source database server.
INFO 2026-03-19T15:34:13.125875Z Running initial data sync using MySQL Shell utilities.
INFO 2026-03-19T15:34:13.126353Z Connection to source database server established.
INFO 2026-03-19T15:34:14.680729Z Acquiring global read lock on source instance.
INFO 2026-03-19T15:34:14.922682Z Read lock has been released from source instance.
INFO 2026-03-19T15:44:11.205775Z Data from source has been dumped successfully.
INFO 2026-03-19T17:06:11.994367Z DUMP_STAGE(SUCCESS): Finished importing data from source database server.
INFO 2026-03-19T17:06:38.739929Z REPLICATION_STAGE(START): Start replicating from source database server.

Appreciate any guidance, thanks a lot!

4

Hi Cristian, Thank you for the additional details and for flagging this issue. I see it’s reviewed by our engineering teams, I’m following closely! Adi

1 Like
5

Hi, I’m currently experiencing the same issue. The full dump phase completes successfully, but it fails during the CDC phase with the same error: unable to connect to 169.254.0.2:3306.

I’ve already tried configuring the PSC network attachment to auto-accept connections and also temporarily opened the firewall to allow all IPs on port 3306 (to rule out any firewall-related issues), but the problem still persists.

My use case is migrating data from a MySQL instance running on a GCP VM to Cloud SQL within the same project.

6

Hi Adi, hope you’re doing well.

Just wanted to check in to see if there are any updates on this matter. Thanks a ton!