Amazon RDS instance recovery during mysqldump
This is a confirmed bug with Amazon RDS.

Reply from Amazon on the 6th Jan 2020:
&quot;Starting with MariaDB 10.2.2 resizing the buffer pool is performed in chunks determined by the size of the innodb_buffer_pool_chunk_size variable. Hence the buffer pool size must be a multiple of innodb_buffer_pool_chunk_size * innodb_buffer_pool_instances, since innodb_buffer_pool_size is set to 1.5 GB the behavior is to round off to 1GB as the &quot;innodb_buffer_pool_instances&quot; is set to 8.&quot;

Original Answer:
On the &quot;db.t2.small&quot; MariaDB instance, it has 2GB of RAM, but innodb_buffer_pool_size is being incorrectly set to 2GB.
This means MariaDB will crash when the InnoDB buffer pool fills with too much data.
The temporary solution is to change the Parameter Group so:
innodb_buffer_pool_instances = 12

If you want to get an ETA from Amazon, ask them to check Case 6411919871, from the 5th September 2019.
I did have to eventually pay them $29 to raise a &quot;Technical&quot; bug report, the original report was raised in August, both with Accounts, and on their Forum:
https://forums.aws.amazon.com/thread.jspa?messageID=913625