Dear Devs We've encountered a problem trying to run a workflow on our local Galaxy instance, which is resulting in an "uncaught exception in exposed API method" message displayed in the Galaxy window. The most trivial workflow exhibiting the problem consists of a single 'cut' task, where the output of the task is configured to change the datatype to "interval", and to explicitly assign the chrom, start and end columns to 1,2 and 3. Attempts to run this workflow generate the API exception. If the workflow is updated so that the column assignments are no longer attempted then the workflow is able to start without apparent problems. Our local Galaxy instance is a bit out of data (18.09) but I have been able to reproduce this error on Galaxy main so it looks like it also affects later versions. The failing workflow can be accessed on main via: https://usegalaxy.org/u/pjbriggs/w/cut-workflow-reassign-columns-fails-with-... The same workflow with the column assignment removed is accessible via: https://usegalaxy.org/u/pjbriggs/w/cut-workflow-no-column-reassignment (Main offers two variants of the 'cut' tool - as far as I can tell this problem happens with both.) Apologies if this has already been reported elsewhere - any suggestions for a workaround appreciated. Thanks, Peter -- Peter Briggs peter.briggs@manchester.ac.uk Bioinformatics Core Facility University of Manchester B.1083 Michael Smith Bldg Tel: (0161) 2751482