I created a field to display the whole route of several photos in a point layer in order to be able to visualize them on the map. I try to do so by using this expression:
concat('C:\Users\DIDAC\Documents\CONSULT\EIA OLIVERES CLARAMUNT\treball camp\fotos\IGN\',"file_name")
"file_name" being the name of every photo.
Here's the error message: "syntax error, unexpected Unknown_CHARACTER"