This error is raised if the conflict table for an article listed in sysmergearticles (Transact-SQL) does not actually exist. The error can occur when you attempt to add a column to or drop a column from a table published for merge replication.
Execute DBCC CHECKDB (Transact-SQL) on the database with the missing conflict table to verify there are no data consistency issues.
If the conflict table is missing on a Subscriber, drop the subscription and recreate it. If the conflict table is missing on a Publisher, drop all subscriptions, drop the publication, and then recreate the publication and all subscriptions. For more information, see Publishing Data and Database Objects and Subscribing to Publications.