A common error when handling files in 4D is the error "a valid POSIX path was expected," especially in 4D 20 R7. This error is usually caused by the command File when an invalid path is passed as an argument. Following is an example code that causes the error:

var $docRef : Time var $selectedFile : 4D.File $docRef:=Open document(""; Read mode) $selectedFile:=File(document; fk posix path)

According to the release notes of 4D 20 R7, there have been changes in the File command when checking the syntax of the path parameter:

"The File command (as well as 4D.File.new()) is stricter when it comes to checking the syntax of the path supplied as a parameter."

Please read more about this behavior change in the official 4D documentation.

The solution to this issue is to pass a path in POSIX syntax to the File commands. For that purpose, we will need the command Convert path system to POSIX. Here is the complete code that does not raise any error:

var $docRef : Time var $selectedFile : 4D.File $docRef:=Open document(""; Read mode) $documentPosix:=Convert path system to POSIX(document) $selectedFile:=File($documentPosix; fk posix path)

If you are using 4D 20 R7 or posterior 4D version, please make sure to use this syntax to avoid the mentioned error.