The WP 2.7.1 Dashboard informs the user of new WP versions 🙂 I decided to try the automatic upgrade…
After having made the database and filesystem backups, I chose „automatic upgrade“, which worked quite nicely. Then I logged out and in again and the database got upgraded. No problems (visible) so far …

The Apache error.log showed two errors repeating over and over:

PHP Warning: gzinflate(): data error in wordpress-2.8/wp-includes/http.php on line 1787

[error] WordPress database error You have an error in your SQL syntax.

The WordPress support recommends a manual upgrade, because I might have only partially upgraded.
Thus I created a new WP directory and extracted the latest WP archive, copied over plugins, themes, uploads, uploads-*, wp-config.php, .htaccess and deactivated all plugins. Then switched the WP directory to the newly created one and watched the Apache log for errors: everything fine, no more errors.
But after re-activation of all plugins all errors were back.
I deactivated all of them again and activated one by one until I found my problematic plugins:

• My Link Order: Needed removal and re-installation for patching some WP files, which doesn’t happen during installation of the plugin, but when you open the settings dialogue in Links on the dashboard: „wp-includes/taxonomy.php has been patched successfully“ 😛 After that message no more errors and the links appear again.
• last.fm for WP: causes the gzinflate data error even on the authors homepage, so I left it deactivated for now and use the lastfm RPS plugin.

Thanks again to all the WP developers for the upgrade and see you next round …