
Hi @Lee Seidel
I'm glad to hear you solve the problem, if you have any issue about SharePoint, you are welcome to raise a ticket in this forum.
By the way, since the Microsoft Q&A community has a policy that "The question author cannot accept their own answer. They can only accept answers by others.". and according to the scenario introduced here: Answering your own questions on Microsoft Q&A, I would make a brief summary of this thread:
Issue Symptom:
Collection admin on SharePoint 2016 on premise. Tried renaming DocumentSet in UI - it lets you enter info and save but nothing changes. Used the WebDav UNC to do the rename via file explorer and get error message that the file name is not valid.....even if I just add 1 character or remove one character. I am able to rename the DocumentSet using SharePoint Designer.-
Current status:
I found a workaround for the user which leads me to think it has something to do with how the web ui calls to make the rename and may be related to the large number of files within each docset that must be renamed as the option to prefix the file name with the docset name is set to on.
Switching the view to quick edit allows the folder to be renamed without issue. I think the rename in quick edit is similar to call made when in SPD vs. what is done in the standard UI rename/property update.
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