The 4.1.0 release includes the following backwards incompatible changes.

Ontologies

http://fedora.info/definitions/v4/indexing#

"Indexable" predicate

indexing#indexable
indexing#Indexable

Full diff of changes to the ontologies between 4.0.0 and 4.1.0

Configuration properties

Logging

When configuring components to log, the following property names have been changed. See logging documentation.

log.fcrepo.*
fcrepo.log.*

ModeShape / Infinispan

These updates will likely not impact most administrators, but are found in following internal configuration files:

fcrepo.activemq.dir => fcrepo.activemq.directory
fcrepo.binary-store-path => fcrepo.binary.directory
fcrepo.infinispan.cache_configuration => fcrepo.ispn.configuration
fcrepo.ispn.CacheDirPath => fcrepo.ispn.cache
fcrepo.ispn.alternative.CacheDirPath => fcrepo.ispn.alternative.cache
fcrepo.ispn.binary.CacheDirPath => fcrepo.ispn.binary.cache
fcrepo.ispn.binary.alternative.CacheDirPath => fcrepo.ispn.binary.alternative.cache
fcrepo.ispn.repo.CacheDirPath => fcrepo.ispn.repo.cache
fcrepo.minter.config => fcrepo.spring.minter.configuration
fcrepo.modeshape.index.location => fcrepo.modeshape.index.directory

Further description of updates can be found in the description associated with this pull request.