huge number of 500 errors for googlebot

I just searched for “500 ” in my access log and realized that almost all (and there’s a lot of them) the 500 errors are for googlebot.

All the links seem to work when I try to access it with my browser. I can’t think what could be the reason. I have no errors.txt file. I’m not an expert on reading log files so here is one sample:

… GET /index.php/category/manufacturers/garmin/ HTTP/1.1″ 500 4439 “-” “Mozilla/5.0 (compatible; Googlebot/2.1; +https://www.google.com/bot.html)”

In case you need it, the site is Navigadget.