@
Alaa - No problems, I'll use screen shots so we get the ducks lined up right on the pond.
This is my Location column definition
This is my Virtual Libraries column definition
This is my Has Location virtual library definition
This is my list of columns that get shown in the book list
And this is the result - after a library switch or stop start to get rid of the error messages.
Those spurious error messages should be reported as a bug at
Bugs : calibre. Would be better if you did that, because you have it on a real library, whereas mine is on my kitchen sink test library. Include a link to this threat in the post.
BR