File.move throws an error

Execute a simple File.move(oldFilePath,newFilePath,true) where both files are in the same directory but it doesn't work at all : The error is throwed from the file src/lib/corelib/jsextensions/file.cpp :

if (!QFile(sourceFile).isReadable())
return context->throwError(QString(QLatin1String("Could not
move '%1' to '%2': ""Source file is not accessible."))
.arg(sourceFile, targetFile));

When move replaced to copy, it works.