Error: 21451, Severity: 16, The %s %s (%s) login (%s) password has been changed.
Error: 21452, Severity: 10, Warning: The %s agent job has been implicitly created and will run under the SQL Server Agent Service Account.
Error: 21454, Severity: 16, The internal procedure sp_MStran_is_snapshot_required must be executed at the Distributor if the @run_at_distributor parameter has a value of 1. If the problem persists, contact Microsoft Customer Support Services.
Error: 21456, Severity: 16, Value provided for parameter %s is not valid.

Error: 21460, Severity: 16, The primary key for source table “%s” includes the timestamp column “%s”. Cannot create the article for the specified publication because it allows updating Subscribers.
Error: 21481, Severity: 16, Cannot create replication subscription(s) in the master database. Choose another database for creating subscriptions.
Error: 21482, Severity: 16, %s can only be executed in the “%s” database.
Error: 21484, Severity: 16, Article validation was requested for snapshot publication “%s”. Article validation is only valid for transactional publications.

Error: 21485, Severity: 16, Tracer tokens cannot be posted for a snapshot publication.
Error: 21486, Severity: 16, An error occurred while logging the tracer token history information. The tracer token could not be posted.
Error: 21487, Severity: 16, An error occurred while inserting the tracer token to the log. The tracer token could not be posted.
Error: 21488, Severity: 16, No active subscriptions were found. The publication must have active subscriptions in order to post a tracer token.
Error: 21489, Severity: 16, A database ‘%s’ already exists. If you intend this to be your distribution database set @existing_db = 1.
Error: 21490, Severity: 16, The value specified for the %s parameter of sp_mergearticlecolumn must be ‘%s’. A value of ‘true’ is allowed only when this procedure is called by another replication procedure. Either set the value of the @schema_replication parameter to ‘false’ or do no
Error: 21499, Severity: 16, The procedure %s failed to %s the resource %s. Server error = %d.
Error: 21500, Severity: 10, Invalid subscription type is specified. A subscription to publication ‘%s’ already exists in the database with a different subscription type.
Error: 21501, Severity: 10, The supplied resolver information does not specify a valid column name to be used for conflict resolution by ‘%s’.
Error: 21502, Severity: 10, The publication ‘%s’ does not allow the subscription to synchronize to an alternate synchronization partner.
Error: 21503, Severity: 10, Cleanup of merge meta data cannot be performed while merge processes are running. Retry this operation after the merge processes have completed.
Error: 21504, Severity: 10, Cleanup of merge meta data at republisher ‘%s’.’%s’ could not be performed because merge processes are propagating changes to the republisher. All subscriptions to this republisher must be reinitialized.

This is applicable on below versions of SQL Server

SQL Server 2005
SQL Server 2008 R2
SQL Server 2012
SQL Server 2014

Hope this was helpful.

Thanks,
SQLServerF1 Team
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