SSRS subscription fails with Protocol violation

Question

We have SSRS reports with multiple subscriptions - recently we have been having some of the subscription fail with protocol violation when running as scheduled. If we manually rerun the subscriptions they work.

The log file shows the following error:

notification!WindowsService_4!1d04!12/16/2021-02:00:15:: i INFO: Handling subscription 19ff974f-f006-4e61-9e85-fcbeacb934bb to report BIXXXXX Tender Report, owner: DDDD\XXXXXXXXXX, delivery extension: Report Server Email.
library!WindowsService_4!1d04!12/16/2021-02:00:15:: i INFO: RenderForNewSession('/Reports/UAT/BIXXXXX Tender Report')
library!WindowsService_4!1424!12/16/2021-02:00:15:: i INFO: Initializing SessionTimeout to '600' second(s) as specified in Server system properties.
library!WindowsService_4!38d4!12/16/2021-02:00:15:: i INFO: Initializing EnableExecutionLogging to 'True' as specified in Server system properties.
library!WindowsService_4!1424!12/16/2021-02:00:15:: i INFO: Initializing EnableExecutionLogging to 'True' as specified in Server system properties.
library!WindowsService_4!38d4!12/16/2021-02:00:15:: i INFO: Initializing StoredParametersThreshold to '1500' characters as specified in Server system properties.
library!WindowsService_4!1424!12/16/2021-02:00:15:: i INFO: Initializing StoredParametersThreshold to '1500' characters as specified in Server system properties.
emailextension!WindowsService_4!38d4!12/16/2021-02:00:17:: e ERROR: Error sending email. Exception: System.AggregateException: One or more errors occurred. ---> System.Net.Mail.SmtpException: The server committed a protocol violation The server response was:
at System.Net.Mail.SendMailAsyncResult.End(IAsyncResult result)
at System.Net.Mail.SmtpClient.SendMailCallback(IAsyncResult result)

Nothing has changed with our SMTP or Report server.

Answer 1

Hi @Roland Goldsack ，
This error message looks like an error occurred when the subscription request was delivered to the SMTP server. The reason for the error may be related to the authentication mechanism. What normally happens is that the server offers a number of authetication options, and the client choses which one it is going to use. The behaviour from there should be determined by the protocol chosen.
You could enable logging for System.Net.Mail. Then view the log file. This will show you exactly what is happening during the SMTP layer. For more information. plase refer to: How do I create a log file of the SMTP session?

At the same time, please check whether there are related error messages in the Event viewer which will help to troubleshoot.

Best Regartds，
Joy

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Answer 2

Hi - any solutions to this error?

br Andreas

Answer 3

Hello,

Sorry for delay.

It was a TLS mismatch and we had to implement the registry settings on our SSRS servers which corrected he issues.

The changes were from the following link:
https://learn.microsoft.com/en-us/answers/questions/184492/sql-server-2016-database-mail-cannot-send-email-sm.html

Hope it helps others resolve the issues.