@ aoliveira: which build of LimeSurvey v1.87+ did you use for upgrade? ==> The latest stable plus release is build 8374 ==> can you reproduce the problem with this build?

I tried with build 8243 and 8366.
I will try to download the latest build and perform the migration. Will post results after. Thanks

HI,
I downloaded the last build 8374 and tried upgrading with no success.
I also tried a new installation from scracth (new website, new database)and also had the same error in tha admin page (PHP Notice: Undefined variable: updatecheckperiod in C:\Inetpub\wwwroot\limesurvey187plus-build8374-20100211\common.php on line 287 )
I even tried to hide the notice by changing PHP ini file replacing the line
error_reporting = E_ALL & ~E_DEPRECATED
with
error_reporting = E_ALL & ~E_DEPRECATED & ~E_NOTICE & ~E_WARNING

I think I have the solution ;-)

In file comon.php, the access to the variable updatelastcheck should be preceded by a '@' instead of a '$' which I suppose in PHP results in not raising an error if the variable is null...
if ($sourcefrom == "admin" && $buildnumber != "" && @updatecheckperiod>0 && @updatelastcheck<date_shift(date("Y-m-d H:i:s"), "Y-m-d H:i:s", "-".$updatecheckperiod." days"))
{
updatecheck();
}

So, I just replaced $updatelastcheck by @updatelastcheck and managed to access the admin area of the site and, in the globalseeting page, manage to check for updates...

Do you agree?

I am sorry, but your fix is bogus.
The upgrade errors can be safely ignored but need to be fixed

The notices are caused by an incorrect update - you did not replace config-
defaults.php with the new version.

Thanks for your feedback.
I was out last week so I could not answer you.
I tried to upgrade a minute ago (keeping the config-defaults.php file) but it is still missing one variable:
"PHP Notice: Undefined variable: debug in C:\Inetpub\wwwroot\limesurvey187plus-build8374-20100211\common.php on line 41 PHP Notice: Undefined variable: debug in C:\Inetpub\wwwroot\limesurvey187plus-build8374-20100211\common.php on line 46 "

Insert the line

$debug=0;

in your config.php.