In the case of read preference "primary", the "NO_MAX_STALENESS_SUPPORT" error condition should be a warning, not a hard error. The config "max_staleness" is only relevant in the context of connections to secondaries, so there is no harm in just ignoring it for primaries. I had an issue where I changed my read preference to primary (i.e. in response to an urgent issue), and my app couldn't start b/c of the max staleness config.

In addition, "SMALLEST_MAX_STALENESS_SECONDS" rather than being an error should just be coerced to the smallest value (90 sec) and log a warning.