Finally decided to upgrade from 2009 to 2010, online using the applet. After a few minutes, I got "Installation failed" with the address of the installation log. The last few lines of the log are:

installing perl-CPANPLUS-0.900.300-1mdv2010.1.noarch.rpm perl-Module-CoreList-2.310.0-1mdv2010.1.noarch.rpm perl-Module-Signature-0.630.0-1mdv2010.1.noarch.rpm from /var/cache/urpmi/rpms
starting installing packages
created transaction for installing on / (remove=0, install=0, upgrade=3)
removing installed rpms (perl-CPANPLUS-0.900.300-1mdv2010.1.noarch.rpm perl-Module-CoreList-2.310.0-1mdv2010.1.noarch.rpm perl-Module-Signature-0.630.0-1mdv2010.1.noarch.rpm) from /var/cache/urpmi/rpms
unlocking urpmi database
unlocking rpm database
$MIRRORLIST: media/contrib/release/perl-Module-Signature-0.630.0-1mdv2010.1.noarch.rpm
restarting urpmi
*** This build of Glib was compiled with glib 2.24.1, but is currently running with 2.20.1, which is too old. We'll continue, but expect problems!
/usr/bin/perl: symbol lookup error: /usr/lib/perl5/vendor_perl/5.10.1/i386-linux-thread-multi/auto/Glib/Glib.so: undefined symbol: g_malloc0_n

There were a few more lines beginning "This build of Glib", so evidently there were indeed problems. Although given the option to retry, I thought it best not to.

Everything on the system seems to be in order, except that MCC is not working - which is unfortunate, as I tend to rely on it. The little blue arrow has gone, replaced by the orange symbol meaning something like "updates accepted", but I daren't close the system down in case something is screwed up.

I gather that Glib is a low-level core library that forms the pasis for GNOME. but I'm using KDE.

And before you ask, I did check that the original system was fully up-to date.

Anyone got any suggestions? I've searched around, and can't find any reference to this problem.

After some further thought, entered the command
rpm -qa | grep -i | glib
which produced this list:

libtaglib1-1.5-5mdv2009.1
taglib-extras-0.1.2-1.1mdv2009.1
perl-Glib-1.222-1mdv2010.1
libpulseglib20-0.9.15-2.1mdv2009.1
libdbus-glib-1_2-0.80-1mdv2009.1
libpyglib2.0_0-2.16.1-3.1mdv2009.1
glibc-2.11.1-8mnb2
libglib1.2-1.2.10-22mdv2009.1
libavahi-glib1-0.6.24-2mdv2009.1
libpoppler-glib4-0.10.6-1.1mdv2009.1
libglib2.0_0-2.20.1-1.1mdv2009.1
glibc-devel-2.11.1-8mnb2
libamarok_taglib1-2.0.2-2mdv2009.1
libglibmm2.4_1-2.20.0-1mdv2009.1
glib2.0-common-2.20.1-1.1mdv2009.1

Strikes me that something here needs upgrading, but which one? I suspect the perl-Glib one, but I'm already out of my depth.

Glib2 (libglib2.0_0) is used by GTK+2 (libgtk+2.0_0) :
The GTK+2 GUI is used by about 600 applications. Gnome included.

Upgrading from Mandriva 2009 to 2010 :
Should have been done to 2009.1. And then 2010.
But that is probably too late . Some packages are updated.
Best solution : A new install of 2010. Latest is 2010.1 !
: : : When you have made a backup with your important files.

If you want to continue : Try with one package at a time.
Use # 'urpmi <package>' or the 'Package Manager'.
.

Thanks for the reply, knudfl. Sorry if I wasn't as clear as I should have been, through trying to be brief. I originally installed Mandriva from a "Mandriva One 2009.1" CD, then late last November tried to upgrade to 2010 from a "Mandriva One 2010" CD thinking it would be safer than doing it online. It was a disaster, as it kept seizing up. In the end I re-installed from the original 2009.1 CD which was a pain but got back to normal eventually. Put me off upgrading for a long while, though!

So - I still have the 2010 CD, but am reluctant to use it. For a start, it's not clear whether it could be installed over the current OS, or whether it would have to be a "clean" install (perhaps to another partition?). I'd rather not continue one package at a time, as I wouldn't know which packages are required, or in what order. Can't use MCC as it no longer works.

Could I install the latest 2010 online, and if so would it have to be a clean install into some unused partition? I've tried to figure this out from various sources, but all the installation advice seems aimed at those going to Linux from Microsoft, and not to those who are already there but whose knowledge is still hazy.

My one consolation is that all the vital stuff is backed up.

[I do have a Ubuntu 9.10 CD as well, but I'd like to stick with the devil I know . . . ]

After having had a few days to think about it, I conclude that LQ wasn't the right place to ask the question. I was upgrading in response to an oft-repeated invitation from Mandriva, and would have expected it to run smoothly, so what I should have done was ask on Mandriva's own forum - but it's too late now.

I'm going to install the latest Ubuntu, as I have local support for that. It's a solution, but I can't really mark this thread as "solved" as the reason for the fail has not been established.

I am sorry to see you moving from Mandriva to Ubuntu, because I think Mandriva is better (at least for me here).

By default, Mandriva sets up a "/" (system) partition, and a "/home" (user space) partition. If you get the installation DVD, and select the "Install" (not "Upgrade") option, Mandriva will format the "/" (system) partition, but not the "/home" (user space) partition, so you will be installing the 2010.1 packages after erasing the 2009.1 packages.

All your user configuration(s) will be preserved, but the applications will be from the current release. This always works well for me, so I never try anything else.

If it is not yet too late, I hope this helps,

1 members found this post helpful.

Thanks, Ernie, for taking the trouble to post that answer. Your solution is so clear and straightforward that I have no hesitation in marking this thread as 'solved'.

It's too late to be of use to me, as I switched distros a few days ago, but it might well be useful to someone else someday.