Receive error msg. "Lightroom could not process file (path to file name). File will not be opened" when selecting an "Additional external editor" through LR Edit-in function. Also LR will not transfer a file to Photoshop Elements (PSE) either through the Edit-in function. Uninstalled & reinstalled external editor programs but still could not access them through LR. I don't know if it has any bearing on this issue but recently updated to LR v6 (standalone) and added PSE 15 to existing PSE 13. The programs I try to access through the Edit-in function in LR are functioning as I can start them either as standalone program or as a PSE plug-in.