How to fix an error Plone RelStorage using AWS RDS Read replica by psycopg2

Question

We want to use AWS RDS Read replica by psycopg2, but we got an error.

Our env:

• Plone 5
• RelStorage 1.6.3
• psycopg2 2.7.3.2
• AWS RDS PostgreSQL (Read Replica)
• buildout.conf: rel-storage = read-only true

Error:

psycopg2.NotSupportedError: cannot use serializable mode in a hot standby HINT: You can use REPEATABLE READ instead. We set:

default_transaction_isolation repeatable read

How can I do anything?