Summary

When encountering authentication failures using the C driver, we see the failures marked with a DEBUG log level, e.g.:

Mongo C driver event type: DEBUG
Event text: "cluster: Authentication failed: Authentication failed."

or

Mongo C driver event type: DEBUG
Event text: "cluster: Authentication failed: SASL Failure: ..."

Our code does not force an error in the case of DEBUG messages. We only do that for ERROR and CRITICAL log levels which we think would be more appropriate for this type of connection failure.

Versions

We see this in all tested versions of the C driver including 1.14.0 and 1.20.0. We are testing on x86 Linux (RHEL 7, RHEL 8). Our tests are running against 3.6 and 6.0 MongoDB database versions.

Reproducing:

Example connection strings pulled from a trace of our code:

connect string: mongodb://username%40INTRANET.customer.COM:XXXXXXXX@hostname.intranet.customer.com:27180/odsCustomers?ssl=true&authMechanism=GSSAPI&authSource=$external&gssapiServiceName=sysmngtcustlett&socketTimeoutMS=-1
        code=1000
        code=1000, errnum=B172, errid=password_decryption_error
Mongo message: DEBUG: cluster: Authentication failed: Authentication failed.