LoadMask algorithm execution error


New Mantid user here! I’m just reducing some data using a script & files that was working OK a few weeks ago, but I’m now getting a new error.

The error is: Error in execution of algorithm LoadMask: SAXParse Exception: no element found in line 1 column 0. Unable to parse File: in “/user/local/mprogs/InstrumentFiles/merlin/mask_Dec2019.xml”

Which made me think I’d broken the mask file, but it looks ok (haven’t consciously edited it). The mask file is located in the directory mentioned above, as well as the directory I am running the script from.


Hi Siobhan!

Are you able to send the script and relevant mask file to me at daniel.murphy@stfc.ac.uk and I’ll have a look into this!?

Daniel - Mantid Support

As this is a forum (and I believe the issue has been resolved) it is worth including the end solution to this problem.

The error message above is about a mask file being read as empty, which in turn made the LoadMask algorithm fail. Actually the problem was that this file had its permissions changed on IDaaS , so that access was denied to Mantid, and the file could not be read!

Although this was a permissions problem with IDaaS, Mantid should have said so in the Error Message: Here’s an issue raised to solve this problem: Misleading error messages when permissions denied to files · Issue #27823 · mantidproject/mantid · GitHub

I would also like to add that changing the permissions on ISIScompute allowed access to this file on IDaaS