Trying to generate an index with a too long name (> 127 char) with ensureIndex throw MongoCommandException with confusing error message

[y5856]

Using ensureIndex() to create an index the following exception was thrown MongoCommandException with message : Caused by: com.mongodb.MongoCommandException: Command failed with error 27 (IndexNotFound): 'can't find index with key: { ... which is unexpected.

It seems that ensureIndex() calls createIndex() and, if an exception is caught, calls dropIndex() then createIndex() with the same keys.

The first call to createIndex() throws this (as my index name was too long) :
Command failed with error 67 (CannotCreateIndex): 'namespace name generated from index name "<TOO_LONG_FULL_INDEX_NAME>" is too long (127 byte max)' ...

Then dropIndex() tries to drop a non-existing index and throws the IndexNotFound exception.

Propagating the CannotCreateIndex exception would make debugging easier.

[zigzago]

True. I fix it.