Migrating G2 to another server; error when gdata implemented

I installed Gallery 2.3 on another server, imported the old database, and the albums show up fine, all broken images which can be expected, but when I put in the older g2data, the gallery just says there's been an error (and doesn't list what kind of error). I thought I'd been following the instructions on the codex, but I must be doing something wrong. It's been a while since I've had to tinker with web sites.

Gallery version (not just "2"): 2.3
PHP version (e.g. 5.1.6): 5.2.17
PHPInfo Link (see FAQ):
Webserver (e.g. Apache 1.3.33): Apache (doesn't say version)
Database (e.g. MySql 5.0.32): 5.5.23
Activated toolkits (e.g. NetPbm, GD): NetPbm, GD, Imagemagick
Operating system (e.g. Linux): Linux CentOS
Browser (e.g. Firefox 2.0): Chrome 20.0.1132.57 m

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NOT a "Twilight" fan... Just a fan of sunsets.

It wasn't 777 but it is now. Still the same error, though. I deleted the cache folder and uploaded everything else to the g2data folder beforehand, except for versions.dat. It was missing the last .(number) on the old one, and the new one had the same version, but that extra third .(number) at the end.

Out of curiosity I went to /upgrade/ to see what it might say.

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NOT a "Twilight" fan... Just a fan of sunsets.