It's a python type error
Python error is telling you that a type in this line is wrong. It's getting a list instead of BMVert
Note this piece of code comes from your question and is WRONG
verts=[myarray, myarray1]
since verts is expecting a list of BMVerts (as pointed out in the documentation you linked) without even seeing your code it suggests myarray, myarray1 are both lists.
Agree with sentiment here to post code
Recommended change
If both myarray, myarray1 are lists of verts sum them
verts = myarray + myarray1
I did google for few hours and could not find any usefull help Anyway your code gives me the same error verts=[myarray, myarray1] TypeError: verts: expected (BMVert), not 'list'
I used your piece of code to combine the variables vertstomerge = [verts_start_a, verts_start_b, verts_start_c] Then I did this bmesh.ops.remove_doubles(bm, verts=vertstomerge dist=0.001 ) Error TypeError: verts: expected (BMVert), not 'list'
No I recommended adding them together. Could it be that type(verts_start_a) b, c, d is a list?, if it is it will lead to a type error, getting a list, expecting a BMVert.
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Tip: Search stackoverflow, or google on the cause of errors. Probably find the solution quicker than writing this question.