# ERROR: vtkMultiBlockDataSetStructure does not match. You must use CopyStructure before calling this method.

**URL:** https://discourse.paraview.org/t/error-vtkmultiblockdatasetstructure-does-not-match-you-must-use-copystructure-before-calling-this-method/1940
**Category:** Development
**Created:** [May 28, 2019, 1:38pm UTC](https://discourse.paraview.org/t/error-vtkmultiblockdatasetstructure-does-not-match-you-must-use-copystructure-before-calling-this-method/1940 "2019-05-28T13:38:22Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![sharon](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/s/67e7ee/32.png) [@sharon](https://discourse.paraview.org/u/sharon)
#### Post date: [May 28, 2019, 1:38pm UTC](https://discourse.paraview.org/t/error-vtkmultiblockdatasetstructure-does-not-match-you-must-use-copystructure-before-calling-this-method/1940/1 "2019-05-28T13:38:22Z")

</div>

Dear Experts,  
my reader read many files by parallel and all data will be converted into vtkPolyData then add into vtkMultiBlockDataSet, it works OK, but sometimes, paraview report below error:

ERROR: In paraview\VTK\Common\DataModel\vtkDataObjectTree.cxx, line 377  
vtkMultiBlockDataSet (000001D72A9B4E20): Structure does not match. You must use CopyStructure before calling this method.

Why it pop this error?  
How to solve it?

Best Regards,  
Sharon