arangosh> a1 = db.example.insert({ a : 1 }); { "_id" : "example/17691", "_key" : "17691", "_rev" : "_WnWW90W--_" } arangosh> a2 = db.example.replace(a1, { a : 2 }); { "_id" : "example/17691", "_key" : "17691", "_rev" : "_WnWW90a--_", "_oldRev" : "_WnWW90W--_" } arangosh> a3 = db.example.replace(a1, { a : 3 }); [ArangoError 1200: precondition failed]