On one particular history, I see this. I am at 035583d94b11<https://bitbucket.org/galaxy/galaxy-central/changeset/035583d94b11200276aed333a859b8e49b64429f> I don't know why this happens on this history… I cloned it, then re-ran one step. I hope this stacktrace is helpful: Exception happened during processing of request from ('127.0.0.1', 56949) Traceback (most recent call last): File "/mnt/ngswork/galaxy/galaxy-dist/eggs/Paste-1.6-py2.6.egg/paste/httpserver.py", line 1053, in process_request_in_thread self.finish_request(request, client_address) File "/usr/lib/python2.6/SocketServer.py", line 320, in finish_request self.RequestHandlerClass(request, client_address, self) File "/usr/lib/python2.6/SocketServer.py", line 615, in __init__ self.handle() File "/mnt/ngswork/galaxy/galaxy-dist/eggs/Paste-1.6-py2.6.egg/paste/httpserver.py", line 432, in handle BaseHTTPRequestHandler.handle(self) File "/usr/lib/python2.6/BaseHTTPServer.py", line 329, in handle self.handle_one_request() File "/mnt/ngswork/galaxy/galaxy-dist/eggs/Paste-1.6-py2.6.egg/paste/httpserver.py", line 427, in handle_one_request self.wsgi_execute() File "/mnt/ngswork/galaxy/galaxy-dist/eggs/Paste-1.6-py2.6.egg/paste/httpserver.py", line 287, in wsgi_execute self.wsgi_start_response) File "/mnt/ngswork/galaxy/galaxy-dist/eggs/Paste-1.6-py2.6.egg/paste/urlmap.py", line 202, in __call__ return app(environ, start_response) File "/mnt/ngswork/galaxy/galaxy-dist/lib/galaxy/web/framework/middleware/xforwardedhost.py", line 21, in __call__ return self.app( environ, start_response ) File "/mnt/ngswork/galaxy/galaxy-dist/eggs/PasteDeploy-1.3.3-py2.6.egg/paste/deploy/config.py", line 164, in __call__ app_iter = self.application(environ, start_response) File "/mnt/ngswork/galaxy/galaxy-dist/lib/galaxy/web/framework/middleware/translogger.py", line 68, in __call__ return self.application(environ, replacement_start_response) File "/mnt/ngswork/galaxy/galaxy-dist/eggs/Paste-1.6-py2.6.egg/paste/exceptions/errormiddleware.py", line 153, in __call__ exc_info) File "/mnt/ngswork/galaxy/galaxy-dist/lib/galaxy/web/framework/middleware/translogger.py", line 67, in replacement_start_response return start_response( status, headers, exc_info ) File "/mnt/ngswork/galaxy/galaxy-dist/eggs/Paste-1.6-py2.6.egg/paste/exceptions/errormiddleware.py", line 143, in __call__ app_iter = self.application(environ, start_response) File "/mnt/ngswork/galaxy/galaxy-dist/eggs/Paste-1.6-py2.6.egg/paste/recursive.py", line 80, in __call__ return self.application(environ, start_response) File "/mnt/ngswork/galaxy/galaxy-dist/lib/galaxy/web/framework/middleware/remoteuser.py", line 91, in __call__ return self.app( environ, start_response ) File "/mnt/ngswork/galaxy/galaxy-dist/eggs/Paste-1.6-py2.6.egg/paste/httpexceptions.py", line 632, in __call__ return self.application(environ, start_response) File "/mnt/ngswork/galaxy/galaxy-dist/lib/galaxy/web/framework/base.py", line 169, in __call__ return body( environ, start_response ) File "/mnt/ngswork/galaxy/galaxy-dist/lib/galaxy/web/framework/__init__.py", line 858, in render template.render_context( context ) File "/mnt/ngswork/galaxy/galaxy-dist/eggs/Mako-0.4.1-py2.6.egg/mako/template.py", line 319, in render_context **kwargs) File "/mnt/ngswork/galaxy/galaxy-dist/eggs/Mako-0.4.1-py2.6.egg/mako/runtime.py", line 692, in _render_context _exec_template(inherit, lclcontext, args=args, kwargs=kwargs) File "/mnt/ngswork/galaxy/galaxy-dist/eggs/Mako-0.4.1-py2.6.egg/mako/runtime.py", line 718, in _exec_template callable_(context, *args, **kwargs) File "/mnt/ngswork/galaxy/galaxy-dist/database/compiled_templates/root/history.mako.py", line 306, in render_body __M_writer(unicode(render_dataset( data, data.hid, show_deleted_on_refresh = show_deleted, for_editing = True ))) File "/mnt/ngswork/galaxy/galaxy-dist/database/compiled_templates/root/history_common.mako.py", line 553, in render_render_dataset visualizations = data.get_visualizations() File "/mnt/ngswork/galaxy/galaxy-dist/lib/galaxy/model/__init__.py", line 1251, in get_visualizations return self.datatype.get_visualizations( self ) File "/mnt/ngswork/galaxy/galaxy-dist/lib/galaxy/datatypes/tabular.py", line 312, in get_visualizations for col_type in dataset.metadata.column_types: TypeError: 'NoneType' object is not iterable brad -- Brad Langhorst langhorst@neb.com<mailto:langhorst@neb.com>