neo4j REST 'Server got itself in trouble' - neo4j

Question

I am running a very basic test to check my understanding and evaluate neo4j REST server (neo4j-community-1.8.M07). I am using Neo4j Python REST Client.
Each test iteration starts with a random strings for the source node name and the destination node name. The names contain only letters a..z and numbers 0..9 (oddly enough, I never got it to fail if I use A..Z and 0..9). The name may be from one char to 36 chars long and there are no repeating chars. I create 36 nodes, where the 1-st node name is only one char long and the 36-th node name has 36 chars. Then I create relations between all nodes. The name of each relation is the concatenation of the source node name and the destination node name. The final graph has 37 nodes (1 reference node and 36 nodes with names from one char to 36 non-repeating chars) and 1260 relations. Before each test iteration I clear the graph, so that it has only one (the reference) node.
The problem is that after several successful iterations neo4j REST server crashes:
Error [500]: Internal Server Error. Server got itself in trouble.
Invalid data sent
The query that crashes the system can be different - here is an example of a query_string that caused a problem:
START n_from=node:index_faqts(node_name="h"),
n_to=node:index_faqts(node_name="hg2b8wpj04ms")CREATE UNIQUE
n_from-[r:`hhg2b8wpj04ms` ]->n_to RETURN r
self.cypher_extension.execute_query( query_string )
I spent a lot of time trying to find a trend, but in vain. If I did something wrong with the queries none of the tests would ever work. I have observed crashes for number of successful test cycles between 5 and 25 rounds.
What might be causing neo4j REST server to crash?
P.S. Some details...
The nodes are created like this:
...
self.index_faqts[ "node_name" ][ p_str_node_name ] =
self.gdb.nodes.create( **p_dict_node_attributes )
...
Just in case - before issuing the query to create a new relation I check the graph to make sure that the
source and the destination nodes exist. That check never failed.

Answer 1

You are using too many relationship-types, currently the limit is at 32k. Might be patched in Neo4j if you have a valid use-case.