The row was not found at the Subscriber when applying the replicated commandClearly, this issue is because the row to be updated on subscriber does not exist any longer while Distribution Agent is trying to propagate it. Therefore, there is a need to fix it as soon as possible to prevent the replication queue from growing so much. To solve this case, we must review the pending commands inside the 'distribution' database by using 'sp_browsereplcmds' in order to identify the affected transaction(s) and row(s), and then insert the missing row manually in the subscriber (or delete the command from queue, however, this recommendation can be taken into account only if someone deleted the row by mistake or you do not need it anymore).
Another technique we have is to use the 'SkipErrors' parameter which allows to skip errors of a certain type (for this issue the error number is 20598), which means that the affected transaction is simply ignored and skipped. Keep in mind that these sorts of error must be treated with extreme caution and a correct understanding of the situation.
That is all for now, let know any remark you may have. Thanks for reading.