Issue : Today I came across a issue in Which the User had a List with many columns and One of the column Which was a look up column was corrupted
Error: "Unknown Error"
We were not able to Delete or edit the column
After a lot of research we found a work around to delete the Column
Checked the Url and found the below
/_layouts/FldEditex.aspx?List=%7B37920121%2D19B2%2D4C77%2D92FF%2D8B3E07853114%7D&Field=Product%5Fx0020%5FDescription
Which is a wrong url it should be
/_layouts/FldEdit.aspx?List=%7B37920121%2D19B2%2D4C77%2D92FF%2D8B3E07853114%7D&Field=Product%5Fx0020%5FDescription
Resolution/Workaround : Just remove ex from FldEditex.aspx => FldEdit.aspx
And you will be able to get to the inside of the column where you can edit or Delete the column .
Cause – Unknown