When I use one of GFF tool (
Filter GFF data by attribute using simple expressions OR
Filter GFF data by feature count using simple expressions OR
, I have this message :
Traceback (most recent call last):
  File "/usr/local/bioinfo/src/galaxy/galaxy-dist/tools/filters/gff/gff_filter_by_attribute.py", line 55, in <module>
    attribute_types = from_json_string( sys.argv[4] )
  File "/usr/local/bioinfo/src/galaxy/galaxy-dist/eggs/simplejson-2.1.1-py2.6-linux-x86_64-ucs2.egg/simplejson/__init__.py", line 384, in loads
  File "/usr/local/bioinfo/src/galaxy/galaxy-dist/eggs/simplejson-2.1.1-py2.6-linux-x86_64-ucs2.egg/simplejson/decoder.py", line 402, in decode
  File "/usr/local/bioinfo/src/galaxy/galaxy-dist/eggs/simplejson-2.1.1-py2.6-linux-x86_64-ucs2.egg/simplejson/decoder.py", line 420, in raw_decode
simplejson.decoder.JSONDecodeError: No JSON object could be decoded: line 1 column 0 (char 0)
A couple questions:

Are you seeing this problem on a local instance or on our public server?
Is it happening for all GFF/GTF datasets or just some?