UPSTREAM_NOT_FOUND [519] How do I fix the problem?

Question

Unable to connect to or maintain connection with an instance due to an error. If this instance just started, please try again in 1-2 minutes.

UPSTREAM_NOT_FOUND [519]
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AWS Lightsail is turning an instance, and continues to turn the puser on top of the instance. However, the error UPSTREAM_NOT_FOUND [519] continues to occur. Switching the instance window back and forth several times does not resolve the issue.

Please give me some advice on how to solve it.

Answer

Hello.

Please check the document below, which describes how to troubleshoot the error.  
In my experience, sshd did not start and connection failed.  
https://repost.aws/knowledge-center/lightsail-resolve-ssh-console-errors

UPSTREAM_NOT_FOUND [519] How do I fix the problem?

UPSTREAM_NOT_FOUND [519]

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