I have a model that buffers multiple different features then performs a union on all the buffers and dissolves and gives the final output feature class. This all works great with no issues. I want to add a field to the final output feature class and then calculate total acres. I have a precondition set to require the output to write before attempting to add the field. I've tried add field followed by add calculation but the model always gets hung up on the add field. The dialog box says that the function is completed by the load bar never quits (see attached). I've also tried the Add Geometry Attributes tool with the same issues. I end up having to cancel to processing which just causes Arc to freeze and I have to force close it. I'm working in ArcMap 10.5.1.
Anyone else having this issue or know of a work around without adding and calculating the field outside of the model?
So it sounds like you have one sequential process (buffer-union-dissolve), not two running separately. Removing the precondition from the sequence and just tie the add field/calculate geometry to th output of the dissolve (at least that is what I would do in a script)
I agree with Dan you should not need to have a precondition for this model, unless you are not telling us the full story? May be a screen shot of your model may help? Just feed the output of your dissolve tool into the input of the Add Field, what happens then?