In my case (moving BOINC to a different PC) I usually install BOINC on a new machine (without connecting to WCG), this ensures that BOINC data directory is properly created. Then I copy BOINC data directory from the old machine to the new one, overwriting what was created during BOINC installation.

I'm assuming it's under windows, under other OS would expect it's fairly similar:

1: Locate the BOINC data-directory on current install. (one of the 1st. lines when you starts BOINC).
2: Disable network in BOINC.
3: Shutdown BOINC.
4: Uninstall BOINC.

5: Copy the BOINC data-directory to new location on a different computer.
6: Install BOINC on new computer, making sure to select the data-directory on the new computer where you copied the files.
7: Start BOINC, and it should normally work without any problems.

Note, it's important to copy the files before installing BOINC, to make sure where's no problems with access-rights on the files. This is especially important if installs as service.

Possible problems:
a: Any GPU's, if example moves from Amd to Nvidia or other way around you'll get problems.
b: Project uses homogeneous redundancy, some of the WCG-projects uses this.
c: Optimized applications, most commonly with SETI@home, these can be both Amd/Intel-specific and SSE-version-specific.


Now, personally every time I've moved BOINC-directory to another computer, I've been sitting with N days CPDN-work, where N normally equals multiple weeks (or months), so setting "no new work" and waiting until all work finished isn't really an option.

If you're only running short tasks like for WCG, setting "no new work" is normally good enough.

edit - fixing a small typing-error and added "problems with" to the lines about Access-rights.

Thanks that worked