Remote server returned an error 503 Server Error and 502 Bad Gateway

[smw66]

I get two types of errors for the dataflows in Power BI:

• Error: Encountered user gateway exception: 'OData: Request failed: The remote server returned an error: (503) Server Unavailable. (Service Unavailable).
• Error: Encountered user gateway exception: 'OData: Request failed: The remote server returned an error: (502) Bad Gateway. (Bad Gateway).

The OData source gateways are online and the dataflows have not been changed this week.

Is there anything I can do to fix these errors?

[forums]

Can you please retry the operation?

Due to problems with the setup of the new datacenter, these errors seem to occur intermittently. We are currently investigating the cause and then try to resolve it.

[forums]

The problem with HTTP 503 Server Unavailable seems to occur intermittently.

In the French datacenter Invantive Cloud now uses a load balancer to distribute and direct the load across nodes. The load balancer uses a health check which can be imitated using:

curl -sS -k -H "Host: bridge-online.invantive.com" https://<backend node>:<backend port>/healthtest

However, the SSL-connection can not always be established due the error:

curl: (35) OpenSSL SSL_connect: SSL_ERROR_SYSCALL in connection to <backend node>:<backend port>

This causes the load balancer to consider the backend node to be failed. A few seconds later, the backend node on the next pool is considered healthy again and so on.

An analysis is ongoing what causes the health monitoring to fail intermittently.

[forums]

Curl reports sometimes success using:

*   Trying IP:PORT...
* Connected to IP (IP) port PORT
* ALPN: curl offers h2,http/1.1
} [5 bytes data]
* TLSv1.3 (OUT), TLS handshake, Client hello (1):
} [512 bytes data]
* TLSv1.3 (IN), TLS handshake, Server hello (2):
{ [122 bytes data]
...

However, on failure it reports:

*   Trying IP:PORT...
* Connected to IP (IP) port PORT
* ALPN: curl offers h2,http/1.1
} [5 bytes data]
* TLSv1.3 (OUT), TLS handshake, Client hello (1):
} [512 bytes data]
* OpenSSL SSL_connect: SSL_ERROR_SYSCALL in connection to IP:PORT
* Closing connection
curl: (35) OpenSSL SSL_connect: SSL_ERROR_SYSCALL in connection to IP:PORT

Further investigation reveals that the maximum number of allowed connections to Invantive Bridge Online is too low, since new connections are being rejected:

Connection id "..." rejected because the maximum number of concurrent connections has been reached.

The maximum number of HTTP connections has significantly been extended to allow for more concurrent users in the future. Additional nodes may be added to further spread out the load.

[smw66]

Thank you for the reply! The refreshes are working now.