I've got a local installation of Craft 3.0.37 and Craft Commerce 2.0.0-beta.15 running on MAMP. When completing an order, an empty response is given by the browser. The same thing happens when trying to look at that error from the admin area.
When I look into the MYSQL logs, I see the following error for both situations:
2019-01-13T13:32:43.718637Z 300 [Note] Aborted connection 300 to db: 'DBNAME' user: 'root' host: 'localhost' (Got an error reading communication packets)
I've tried upping the limits of the MYSQL setup, but to no avail.