Fallback to 'select' IO plugin if default plugin cannot be loaded. On UNIX-like systems, default IO backend is 'libevent', which uses third-party library might be not available at the run-time. Read in lcb_cntl(3couchbase) man page in section LCB_CNTL_IOPS_DEFAULT_TYPES about how to determine effective IO plugin, when your code chose to use LCB_IO_OPS_DEFAULT during connection instantiation. The fallback mode doesn't affect application which specify IO backend explicitly.
Skip misconfigured nodes in the list. New lcb_cntl(3couchbase) added to control whether the library will skip nodes in initial node list, which listen on configuration port (8091 usually) but doesn't meet required parameters (invalid authentication or missing bucket). By default report this issue and stop trying nodes from the list, like all previous release. Read more at man page lcb_cntl(3couchbase) in section LCB_CNTL_SKIP_CONFIGURATION_ERRORS_ON_CONNECT
Distribute debug information with release binaries on Windows
Do not use socket after failout. Fixes segmentation faults during rebalance.
Use provided credentials for authenticating to the data nodes. With this fix, it is no longer possible to use Administrator credentials with a bucket. If your configuration does so, you must change the credentials you use before applying this update. No documentation guides use of Administrator credentials, so this change is not expected to affect few, if any deployments.
Do not disable config.h on UNIX-like platforms. It fixes build issue, when application is trying to include plugins from the tarball.