SSL connection has been closed unexpectedly

Question

I have tried twice to load a 300 GB Sql dump into Aurora Severless and both times it failed after two and half hours with the message:  
  
  _SSL connection has been closed unexpectedly_  
  _no connection to the server_  
  _connection to server was lost_  
  
On the AWS Console, there is an event stating that  
  
  _Error restarting database: Could not verify and start postgres_  
  
preceded by a few failed attempts to bring the capacity of the cluster up from 2 to 4 capacity units (I have the max set to 64 units).    
  
I am loading the Sql dump from an EC2 instance (created about 1 year ago) on the same VPC using psql.  The dump was created by a 9.6.20 server (from the Google SQL service).   The GRANTs, REVOKEs, and ALTERs unique to Google are removed before loading.  It is a simple database with 6 tables.   
  
When I try smaller databases (say a 5Gbyte dump), the same pipeline completes fine.   
  
Any suggestions how I could debug this?  
  
Edited by: Saci on Mar 28, 2021 7:20 PM to add italics  
  
Edited by: Saci on Mar 29, 2021 4:18 AM.  Typo

Answer

I made some progress with this issue.  It seems to be an Aurora Serverless problem.  The data loads fine into an RDS Postgres database.   
  
My suspicion is that the transition from one compute capacity to a larger one is causing the problem.  Next I want to try loading the data in Aurora with fixe computing resources.

Answer

Some more progress.  I tried loading the large dump into Aurora and it does so with no problems.  This encouraged me to modified my Aurora Severless instance to have a larger minimum compute capacity, so no transitions would be needed while the database is loading.  This eliminated the error.  
  
I suspect based on these experiments is that the SSL error above is a bug in Aurora Severless: when the engine is loading a large SQL dump, the COPY will fail if the engine switches compute capacity.

SSL connection has been closed unexpectedly

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