The ticket SERVER-117009, which landed in v8.3, enabled the parsing strictness on a couple of cluster parameters, like fleCompactionOptions or internalSearchOptions.
This causes an issue when upgrading: if any unknown field was persisted in a previous version, the node will crash immediately after upgrading the binaries to v8.3.

Therefore, the commit done under SERVER-117009 must be reverted before the release v8.3 rolls out.