I'm trying to merge 23 line feature classes. For reference, they are all from the same source, the National Hydrography Dataset. They are all the same type: lines. When I tried to merge all of them, I got an error that says: "ERROR 002949: The data type of NHDFlowline is not the same as that of previously entered datasets."
I figured maybe one of the feature classes has an error, so I tried multiple merges with different pairs of feature classes. They all got the same error.
I tried writing to a shapefile instead of a feature class. Got the same error.
I can't find any documentation on that specific error. They're the same type, so I'm not sure what the issue is. I have merged NHD line data many times and have never had this issue.
I tried restarting ArcGIS Pro and restarting my computer.