The installation is not valid. Aty least one file is missing (DeviceMapping) WinCCFlex2008

1. Close WinCC Flexible

2. Close following processes in Windows Task Manager: "Hmies.exe", "HmiSmartStart.exe" and "TransferTool.exe”.

3. If available, delete the key in the Windows Registry ("Start" -> "Execute..." -> "Regedit”):

--> HKEY_CLASSES_ROOT\CLSID\{5D0CE850-D909-11CF-91FC-00A0C903976F}

4. Enter following command and execute ("Start" -> "Execute..."):

--> "C:\Program Files\Siemens\SIMATIC WinCC flexible\WinCC flexible

--> 2007\Transfer\TransferTool.exe" /Register

IMPORTANT: If the transfer tool is on another path on your pc, so you have to modify the command!

5. Now check if you have this key in your Registry:

--> HKEY_CLASSES_ROOT\CLSID\{5D0CE850-D909-11CF-91FC-00A0C903976F}

(You need administrative rights! )

6. Check if you can transfer from Flexible now again.

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Of course I had to change 2007 to 2008 folder.
I did it and it works now.

Good luck!

Good day! 

Had a similar problem, the function helped "Rebuild All"!