PATCH ERROR and/or FAILURE TO UPDATE? (Workaround Solution)

Any issues, problems or troubleshooting topics related to installing the Prepar3D client application or it's installer.
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Location: Midlothian, Scotland

Postby Cruachan » Mon Oct 13, 2014 5:45 pm

What follows is a list of revised instructions (refined in places to provide additional clarity) which should allow you to patch Prepar3D if the recommended Patching procedure has failed and/or displays the 'Could not write value Complete to key....' error. This method has been tested successfully moving from version 2.3.11345.0 to 2.4.11570.0. I cannot say whether this will work with future or past versions of Prepar3D but, unless the Patching logic changes, it is likely that it will. However, it would be sensible to wait for posted confirmation before trying it with a future update.

The original version of this guide, with explanations and some additional background information can be found here:


1.. Rename the existing 'Prepar3D v2' folder to 'xxxxxx'.

2.. Create a new temporary 'dummy' folder at the same location and rename it 'Prepar3D v2'.

3.. Backup the following 4 folders to a safe location:

%PROGRAMDATA%\Lockheed Martin\Prepar3D v2

%LOCALAPPDATA%\Lockheed Martin\Prepar3D v2

%APPDATA%\Lockheed Martin\Prepar3D v2

%USERPROFILE%\Documents\Prepar3D v2 Files

Tip: Copy and paste each of the above paths into the Run.. > Open: field for instant navigation to these folders. A Windows Explorer window will open displaying the contents. Change to the 'Lockheed Martin' folder immediately above and there you will see the relevant Prepar3D v2 folder ready for backup.

Tip: Create 4 parent folders at the safe location named 'PROGRAMDATA', 'LOCALAPPDATA', 'APPDATA' and 'USERPROFILE'. Copy the 3 'Prepar3D v2' folders and the 'Prepar3D v2 Files' folder to their respective parent folders. This will serve as a reminder as to what goes where when you restore certain files (see below) or should you feel the need to recover, as part of the rollback, to the previous version of Prepar3D.

4.. Delete those same original 4 folders.

Note: These same 4 parent folders and initial content are recreated by Prepar3D at the next run of the simulator.

5.. Temporarily disable your Antivirus/Anti-spyware/Anti-malware protection.

6.. BEFORE running the Patch Updater file,

Verify the MD5 Checksum to confirm you have a good download:

7.. Now, RUN the Patch Updater.

Either 'IGNORE' or 'OK' any error messages as appropriate. Do not cancel or abort the installation. Allow it to finish.

On my system the time taken from start to finish was approximately 8 minutes. Your experience may be different.

This next step isn't strictly necessary and can be skipped.

8.. Create a copy of the temporary 'dummy' Prepar3D v2 folder which should now contain all the newly extracted patch files and folders. Rename this copy to P3DFiles(BeforeUpdate).

Use this P3DFiles(BeforeUpdate) folder copy as a reference and overwrite all these files with copies of the same files from your original Prepar3D v2 installation which still exists in the 'xxxxxx' folder. This will allow you to rollback to your old installation. The P3DFiles(BeforeUpdate) folder can be deleted later.

9.. You now have 2 options:

a) Perform a multiple selection (Files and Folders) of the entire content of the temporary 'dummy' 'Prepar3D v2' folder and merge it with the existing content of your 'xxxxxx' folder.


b) You can take your time and copy and paste all the files, folder by corresponding folder.

10.. Move the temporary 'dummy' Prepar3D v2 folder to a safe location in case it is needed again.

Now RENAME the 'xxxxxx' folder back to Prepar3D v2

11.. Reboot your computer.

12..... RUN/START: Prepar3D

Be patient as it will take some time to rebuild and load everything at the first run.

Check the Version Number.

13/1.. Run and test a few times before **restoring all the 3rd Party content which, of course, is still in place, but not yet functional. Before doing so, check with the Developers as to whether updates have been issued to ensure ongoing compatibility of their products with the latest updated version of Prepar3D. **Skip this step if you have not installed any Addons.

13/2.. Update FSUIPC, if installed, should you require it to be functional in the latest version of Prepar3D.

13/3.. Remember those folders which were backed up in Step 3? They contain everything you might need (including the file Scenery.cfg) when it comes to, for example, comparing/updating new file content with the old text/script entries.

Backup the newly generated Scenery.cfg and rename it Scenery_default.cfg. Skip if no Scenery Addons installed.

Restore your old Scenery.cfg file to its original exact location. Again, this step is unnecessary if you have not installed any 3rd Party Products that may have added entries to Scenery.cfg

Refer to the first 3 folders backed up in Step 3.

Find and Restore the DLL.XML and EXE.XML files to their original exact locations.

Some Addons may have written entries to these files and will not work unless these are in place and correct. Note they may not yet be present in the updated installation nor, indeed, in your original installation if you have not installed any Addons that require them.

13/4.. Install any 3rd Party Product updates, if required.

13/5.. The file Prepar3D.cfg is a special case. A new file is generated by Prepar3D when it is run following the update. Normally it should be left alone. However, some 3rd. Party Vendors may have written to this file and made some additions (Unlimited Traffic 2, for example). Therefore, it is important to perform a manual compare of the old file's text entries with the new file and update the new file as necessary.

Lockheed Martin may have introduced changes to the updated Prepar3D.cfg file to enhance the simulator's behaviour and performance. Therefore, do NOT simply overwrite the new Prepar3D.cfg with the old version.

Thanks go to Rob for reminding me about this important point.

14..... RUN/START: Prepar3D (Again, be patient as it will have to rebuild the scenery indexes and update the database before beginning the loading phase.)

Job Completed!

Reminder: that this procedure applies to the v2.3 to 2.4 update and repeated testing confirms that it works. Future Patch Updates may behave differently so please wait for posted confirmation before trying this process again.


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Joined: Wed May 07, 2014 9:36 pm

Postby GordonBell » Sun Oct 19, 2014 12:59 pm

thanks mike this helped with updating to v2.4


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