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Home < Projects:SlicerFAQ:RegistrationError

Registration failed with an error. What should I try next?

  • Problem: automated registration fails, status message says "completed with error" or similar.
  • Explanation: Registration methods are mostly implemented as commandline modules, where the input to the algorithm is provided as temporary files and the algorithm then seeks a solution independently from the activity of the Slicer GUI. Several reasons can lead to failure, most commonly they are wrong or inconsistent input or lack of convergence if images are too far apart initially.
  • Fix: open the Error Log window (Window Menu) and click on the most recent (top) entries related to the registration. Usually you will see a commandline entry that shows which arguments were given to the algorithm, and a standard output or similar that lists what the algorithm returned. More detailed error info can be found in either this entry, or in the ERROR: ..." line at the top of the list. Click on the corresponding line and look for explanation in the provided text. If there was a problem with the input arguments or the that would be reported here.
    • for example, running Robust Multiresolution Affine without input will report: "No input data assigned" etc.
  • If the Error log does not provide useful clues, try varying some of the parameters. Note that if the algorithm aborts/fails right away and returns immediately with an error, most likely some input is wrong/inconsistent or missing.
  • if variation does not succeed, try an alternative registration module. Some are more tailored toward particular image modalities and DOF than others
  • check the initial misalignment, if images are too far apart and there is no overlap, registration may fail. Consider initialization with a prior manual alignment, centering the images or using one of the initialization methods provided by the modules
  • write to the Slicer user group ( and inform them of the error. We're keen on learning so we can improve the program. Helpful to copy and paste the error messages found in the Error Log.