I've been migrating a few sites to a new server. 5 of them went perfectly OK but the sixth is giving an "HTTP 500 (Internal Server Error)". So I guess the problem is with this particular site, not with the server.
The sites that went OK are D7 and the one that gives the error is D6. The other difference is that this D6 site has a large database (around 200MB) and I had to migrate through command line (with mysqldump, I tried before with "backup and migrate" module and with phpmyadmin, but both gave errors).
The database migration through command line seems to have worked OK (no errors in the process and looking at the tables in Phpmyadmin everything seems to be in its place) but when I change the settings.php I get always error 500 (in every page, except for /install.php, that obviously says Drupal it's already installed).
I've searched quite a lot for possible solutions for the 500 error and tried a few of them (most related to changing .htaccess), but all without any luck. I've activated error logging for php (by the way, i'm using nginx as server, not apache) and it gave me the following errors in error.log: