@tkf Oh thanks so much, so interesting that it is a bug in Pandas.jl. Hmm, I can open an issue with them. Thanks for always being so helpful and available.
But I am not clear what the underlying problem is. So how am I getting a Union{} type? Like is that for a specific column. When I checked the column datatypes for the original dataframe using unique(eltypes(df)) the list is:
Int64
Union{Missing, Int64}
Float64
Union{Missing, Float64}
Missing
String
So I don’t have any Union{} only types, though that is probably the supertype of the Union. So is the multiple dispatch defaulting to the Union{} type because it does not have an implementation for the specific Union{Missing, Float64} type or something. Or could it be that I have an unimplemented column that is all Missing and that is throwing it off?
I will see if I can dev the Pandas package and step through that section of code to trap the error. If I delete columns one by one, I can find the offending column.