# Merge Blocks filter not working for XDMF multiblock unstructured grids in 5.6.0

**URL:** https://discourse.paraview.org/t/merge-blocks-filter-not-working-for-xdmf-multiblock-unstructured-grids-in-5-6-0/1002
**Category:** ParaView Support
**Created:** [December 4, 2018, 10:03pm UTC](https://discourse.paraview.org/t/merge-blocks-filter-not-working-for-xdmf-multiblock-unstructured-grids-in-5-6-0/1002 "2018-12-04T22:03:07Z")
**Posts on this page:** 5
**Page:** 1

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### Author: ![asmith](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/a/94ad74/32.png) [@asmith](https://discourse.paraview.org/u/asmith)
#### Post date: [December 4, 2018, 10:03pm UTC](https://discourse.paraview.org/t/merge-blocks-filter-not-working-for-xdmf-multiblock-unstructured-grids-in-5-6-0/1002/1 "2018-12-04T22:03:08Z")

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I have an XDMF multiblock unstructured grid opened with the ParaView 5.6.0 binaries.  
After taking a slice I get the following:

 ![slice_before_merge](https://discourse.paraview.org/uploads/default/original/1X/83926c3570f9544fd388c5e592df61815d696cfb.png)

I attempt a Merge Blocks filter and get the following:

 ![slice_after_merge](https://discourse.paraview.org/uploads/default/original/1X/60f842b567d750c1beb062a73adb399ed88899e0.png)

Can anyone else confirm this behavior? This operation worked in previous versions.  
This is observed when ParaView is run in serial or parallel on Linux with both the GUI and osmesa versions.

Thanks,  
Andy

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### Author: ![mwestphal](https://discourse.paraview.org/user_avatar/discourse.paraview.org/mwestphal/32/17_2.png) [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [December 10, 2018, 3:37pm UTC](https://discourse.paraview.org/t/merge-blocks-filter-not-working-for-xdmf-multiblock-unstructured-grids-in-5-6-0/1002/2 "2018-12-10T15:37:33Z")

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This is a bug in the MergeBlock filter.  
[https://gitlab.kitware.com/vtk/vtk/issues/17450](https://gitlab.kitware.com/vtk/vtk/issues/17450)

A workaround would be to use the cell data instead of point data as cell data are not impacted by the bug.

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### Author: ![asmith](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/a/94ad74/32.png) [@asmith](https://discourse.paraview.org/u/asmith)
#### Post date: [December 11, 2018, 2:28am UTC](https://discourse.paraview.org/t/merge-blocks-filter-not-working-for-xdmf-multiblock-unstructured-grids-in-5-6-0/1002/3 "2018-12-11T02:28:15Z")

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Mathieu,

Thank you for the update. I will keep an eye out on that bug on gitlab.

-Andy

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### Author: ![Andy\_Bauer](https://discourse.paraview.org/user_avatar/discourse.paraview.org/andy_bauer/32/5442_2.png) [@Andy\_Bauer](https://discourse.paraview.org/u/Andy_Bauer)
#### Post date: [December 11, 2018, 1:31pm UTC](https://discourse.paraview.org/t/merge-blocks-filter-not-working-for-xdmf-multiblock-unstructured-grids-in-5-6-0/1002/4 "2018-12-11T13:31:36Z")

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Another option is to not use the _Merge Points_ option for the Merge Blocks filter and then use the _Clean to Grid_ filter to merge the coincident points.

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### Author: ![mwestphal](https://discourse.paraview.org/user_avatar/discourse.paraview.org/mwestphal/32/17_2.png) [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [December 12, 2018, 5:29pm UTC](https://discourse.paraview.org/t/merge-blocks-filter-not-working-for-xdmf-multiblock-unstructured-grids-in-5-6-0/1002/5 "2018-12-12T17:29:15Z")

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This has been fixed by @Andy_Bauer and is available in ParaView master.