I have two polygon shapefiles that I need to merge. I applied 'Merge vector layers' tool from Data management in QGIS 3.16, but it took too long to process and I realized a message indicating that one shp has integer field type and the other integer64.

Assuming this is the problem why the process could not be completed, how can I change the data type of one of these layers? And which one should it be?

  • 2
    I usually get that error when merging two layers that have fields with the same name but different data types. Try renaming one of them or use Refactor fields to change type to the same. I dont think the type you choose will matter, I would go with int
    – Bera
    Commented Jan 12, 2021 at 9:47
  • 3
    Integer fits also into integer64 but the largest numbers that integer64 support do not fit into integer.
    – user30184
    Commented Jan 12, 2021 at 9:50

1 Answer 1


I tried Refactor fields and changed the integer64 data type to integer32 and the Merge process completed successfully.

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