Missing apoc procedure

I need to delete all indexes & constraints in my Neo4j database.
Until today I was successfully using the following procedure:

//delete all indexes & constraints
CALL apoc.schema.assert({},{},true) YIELD label, key RETURN *

However, as of today it returns the following msg:


There is no procedure with the name apoc.schema.assert registered for this database instance. Please ensure you've spelled the procedure name correctly and that the procedure is properly deployed.

Any idea what has happen & how could I fix this?


What version of Neo4j?
What version of APOC? (i.e. cypher statement return apoc.version(); )

Does this procedure appear in the output of call apoc.help('schema.assert'); ?