Error message in Merge replication "Call sp_MSensure_single_instance"

Question

Error message in Merge replication "Call sp_MSensure_single_instance"

Gao Peng 26

In replication monitor, I read an error message from a merge replication
"
Command attempted:
{call sp_MSensure_single_instance (N'IZT4N73LFYS1BMZ\FLAG2-flagdata-Flag Data Tables-WIN-5PNEMH7B8TU-642', 4)}

Error messages:
The merge process could not connect to the Publisher 'IZT4N73LFYS1BMZ\FLAG2016:flagdata'. Check to ensure that the server is running. (Source: MSSQL_REPL, Error number: MSSQL_REPL-2147199368)
Get help: http://help/MSSQL_REPL-2147199368
Another merge agent for the subscription or subscriptions is running, or the server is working on a previous request by the same agent. (Source: MSSQLServer, Error number: 21036)
Get help: http://help/21036
"

Then I check the job list in Subscriber's SSMS/SQL Server Agent node, there is no duplicate job so presumably there should be any merge agent running.
And everytime before I start this job, I always stop it first.

Can anyone tell me how to launch an investigation on if there is a hidden subscription/merge agent job. I did delete subscriptions few times, that is real. I should have removed those agent jobs as well.

Seeya Xi-MSFT 16,761 Reputation points

2022-12-28T04:34:43.11+00:00

Hi @Gao Peng ,

We have not received a response from you. Did the reply could help you? If the response helped, do "Accept Answer". If it doesn't work, please let us know the progress. By doing so, it will benefit all community members who are having this similar issue. Your contribution is highly appreciated.

Best regards,
Seeya
Seeya Xi-MSFT 16,761 Reputation points

2022-12-29T07:36:15.057+00:00

Hi @Gao Peng ,

In order to benefit all community members who are having this similar issue, please choose an answer to accept or vote for the answer you think is useful to you. Your contribution is highly appreciated.

Best regards,
Seeya

3 answers

Your answer

Seeya Xi-MSFT 16,761 Reputation points

2022-12-28T04:34:43.11+00:00

Hi @Gao Peng ,

We have not received a response from you. Did the reply could help you? If the response helped, do "Accept Answer". If it doesn't work, please let us know the progress. By doing so, it will benefit all community members who are having this similar issue. Your contribution is highly appreciated.

Best regards,
Seeya
Seeya Xi-MSFT 16,761 Reputation points

2022-12-29T07:36:15.057+00:00

Hi @Gao Peng ,

In order to benefit all community members who are having this similar issue, please choose an answer to accept or vote for the answer you think is useful to you. Your contribution is highly appreciated.

Best regards,
Seeya

Answer 1

Neil 0

Same issue...Merge replication...

I fix the problem with killing the process associated with the erroring subscription, using sp_who & kill #. I start with the largest ID and working "down" (up the query result).

I do not know what is causing this at the moment, & it's only happening for one publication.

I'm going to investigate whether it might have something to do with an application initiating replication synchs outside of the default merge schedule.

0 comments

Answer 2

I've run into the very same issue with a production database.
I checked EVERYTHING (along with ChatGPT/Copilot) - nothing helps.
Interestingly, we've got lots of other subscriptions on the same server as well as the same publisher - even on the same database(!) - and they are working fine, except for only the one failing...

It cannot be an authentication issue - and I could not find any merge replication setup meta data mismatch either.

There is also nothing to find about Microsoft error MSSQL_REPL-2147199368... or on:

Message: {call sp_MSensure_single_instance (N'DEBR-SQL-010-HB-DBWORKS-PubDBWorks-INGU-SQL-01-81', 4)}

2025-07-14 11:12:40.802 Percent Complete: 0

2025-07-14 11:12:40.802 Category:SQLSERVER

Source: DEBR-SQL-010

Number: 21036

If anybody has any idea (except of to recreate the subscription - which we are doing on a separate copy, but it takes a lot of time, even without re-initializing), it would be very helpful.
TKo

Answer 3

Seeya Xi-MSFT 16,761

Hi @Gao Peng ,

When you dropped the subscription and recreated it again the subscriber was able to run the replication agent again.
In addition, please refer to this blog: https://techcommunity.microsoft.com/t5/sql-server-support-blog/how-to-find-sql-server-replication-related-jobs-and-t-sql/ba-p/1530496
Hope this would give you some help.

Best regards,
Seeya

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Gao Peng 26 Reputation points

2022-12-27T10:42:03.707+00:00

Thanks, that post is a masterpiece. There is no redundant jobs/agents after I run the scripts. So I have to use profilier to check those T-sql statements during the agent running. Hope that will have a conclusion for this strange case
Gao Peng 26 Reputation points

2023-01-10T07:18:41.157+00:00

What makes me feel amazing is after I re-install whole sql server bunch of things and re-create the subscription.....It is still saying "call sp_MSensure_single_instance ......." in replication monitor. Any further advice? I confirm there is no concurrent sql agent job running...