On one of my PCs, long time ago I had installed BOINC 7.6.22 this way: Program Directory in Drive C:\ (SSD) and Data Directory in Drive D:\ (HDD). Now the HDD gave up. So I decided to download and install the latest version 7.16.11, completely on Drive C:\
As expected, I could not simply install the new version over the old one. So I tried to run the uninstall routine, which did not work either (obviously simply because there was no access to drive D:\ any more).
So I deleted some BOINC-related files in the windows explorer of Drive C:\ manually, but many of them could not be deleted.
So I opened the registry and deleted everything related to BOINC.
After restarting the PC and beginning with the installation of 7.16.11, I got an error notice saying

Error 2718. Missing package name for product code '{B3B5C017-61CD-4587-9FA8-7E5E2D94810E}

As this looked like a registry entry I suspected that while deleting BOINC-related data from the registry before, I inadvertantly deleted something else which I should not have deleted. So I restored the registry and tried again to install 7.16.11. However, the same error message is showing up again. So obviously this does not have anything to do with the registry.

However, I now have no idea how I can install BOINC. What does "Missing package" mean in this context?

Hope that anyone here can help, thanks in advance[/url]

OK, here goes.

1) 'Missing package'. This is a package of instructions and data used for installing your old version. In short, it's called an 'msi' file, and is normally squirrelled away by Windows so that it can be used again when the time comes to UNinstall the old version, in preparation for installing the new version.

2) HDD failure - 'missing drive D:'. There is one registry key where you need to fix this.

[HKEY_LOCAL_MACHINE\SOFTWARE\Space Sciences Laboratory, U.C. Berkeley\BOINC Setup]
"UpgradingTo"="7.6.22"
"INSTALLDIR"="D:\\BOINC\\"
"DATADIR"="D:\\BOINCdata\\"

Looks like I used the same version as you did!

First, you need to change (or delete) any reference to a D: drive in that 'BOINC Setup' registry branch. The setup program doesn't like imaginary drives.

Second, if you still get the error about the missing package, try installing the old version again - exactly the same old version. If you haven't still got the old setup file, you can download it from https://boinc.berkeley.edu/dl/?C=M;O=D. Scroll down to end 2015 / early 2016, and download the matching version - 32-bit or 64-bit, with or without VBox. Hopefully, this will offer to "repair" your old version, copying the missing files to C:. Let it complete: this will replace the missing msi package as well.

Then, your planned upgrade to v7.16.11 should go smoothly. If not, post again and describe the new state of affairs.

...
Then, your planned upgrade to v7.16.11 should go smoothly. If not, post again and describe the new state of affairs.

Richard, you made my day :-)
The upgrade to 7.16.11 worked perfect!

Thanks you so much for your quick help, best regards