When the content-length filter was introduced in
NIFI-7153, it did not separate Site to Site (S2S) or cluster request replication requests from user-generated requests. With the default value of 20 MB, it is very likely that legitimate requests of this nature will be unexpectedly blocked.
The immediate fix is to change the default value in nifi.properties to empty and only enable this functionality when a value is provided.
A subtask will be opened to investigate if these requests should be excluded from the length limiting filter (either by convention or via an admin-enumerated exclusion list/setting).