[ https://issues.apache.org/jira/browse/COUCHDB-1570?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13486230#comment-13486230 ] 

Jens Alfke commented on COUCHDB-1570:
-------------------------------------

The problem was with BaseCouch's code for updating _local documents; it wasn't stripping out underscored property names like _revisions. I'm still not sure why CouchDB was sending a _revisions property in the PUT, but BaseCouch shouldn't have been storing it, or echoing it back on the next GET. Sorry for the confusion!
                
> Replicator writes corrupt remote checkpoint document on error; breaks replication
> ---------------------------------------------------------------------------------
>
>                 Key: COUCHDB-1570
>                 URL: https://issues.apache.org/jira/browse/COUCHDB-1570
>             Project: CouchDB
>          Issue Type: Bug
>          Components: Replication
>    Affects Versions: 1.2
>         Environment: Mac OS X 10.8.2
>            Reporter: Jens Alfke
>            Assignee: Randall Leeds
>            Priority: Blocker
>             Fix For: 1.3
>
>
> If a 'push' replication receives error responses from the remote server while PUTting documents, it may write a corrupt checkpoint document to the remote server -- its _revisions._ids property is null. Any subsequent attempt to push to that server will cause the replicator to abort with an error when reading that replication document, since it requires _revisions.ids to be an array.
> The only workaround for this, short of deleting the remote database entirely, is to (a) identify the URL of the remote checkpoint document, and (b) delete it from the remote server. Otherwise you will never be able to push to that database again.
> Here's a failed replication attempt:
> $ curl -X POST --user snej :5984/_replicate --header Content-Type:application/json --data '{"source":"demo-shopping-attachments","target":"http://localhost:4984/demo-shopping-attachments","create_target":true}'
> {"error":"doc_validation","reason":"_revisions.ids isn't a array."}
> Here's the contents of the remote checkpoint document, once I identified its ID:
> $ curl :4984/demo-shopping-attachments/_local/5b913befe682d7bd1fbc24b1ce31cbc5
> {"_id":"_local/5b913befe682d7bd1fbc24b1ce31cbc5","_rev":"0-1","_revisions":{"ids":null,"start":0},"history":[{"doc_write_failures":2,"docs_read":2,"docs_written":0,"end_last_seq":207,"end_time":"Sun, 21 Oct 2012 19:40:04 GMT","missing_checked":17,"missing_found":2,"recorded_seq":207,"session_id":"9a24dc37885b5b4e507ea90702b2fecf","start_last_seq":0,"start_time":"Sun, 21 Oct 2012 19:40:04 GMT"}],"replication_id_version":2,"session_id":"9a24dc37885b5b4e507ea90702b2fecf","source_last_seq":207}

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