I had this error when I was in a sharepoint document library, chose a document and then clicked "Edit Properties" on the ribbon. It gave me this "the specified file or folder name is too long. The Url must be less than 260 characters" error.
Steps to get this error, but I am not able to replicate on my other machines.
1. go to a document library
2. choose a column to filter, for example "Modified By" column
3. choose a document, select "Edit Properties" on the ribbon.
Any ideas why this error happens? Thanks!