SERVER-36355: Improve error message when shard key not present in all documents

(cherry picked from commit 9e71e5092e987354516f443db9d3f557f3ebf574)

1 files changed, 3 insertions, 2 deletions

diff --git a/src/mongo/db/s/check_sharding_index_command.cpp b/src/mongo/db/s/check_sharding_index_command.cpp
index 6df603e8709..7c4d2e19b65 100644
--- a/src/mongo/db/s/check_sharding_index_command.cpp
+++ b/src/mongo/db/s/check_sharding_index_command.cpp
@@ -192,8 +192,9 @@ public:
                     continue;
 
                 const string msg = str::stream()
-                    << "found missing value in key " << redact(currKey)
-                    << " for doc: " << (obj.hasField("_id") ? redact(obj) : redact(obj["_id"]));
+                    << "There are documents which have missing or incomplete shard key fields ("
+                    << redact(currKey) << "). Please ensure that all documents in the collection "
+                                          "include all fields from the shard key.";
                 log() << "checkShardingIndex for '" << nss.toString() << "' failed: " << msg;
 
                 errmsg = msg;