Your web server does not appear to support any common database types.

Yes I've seen people run into this elsewhere. Either the "no supported database types" message needs to be extended, or we just document this somewhere (other than troubleshooting).

I would extend the error message. People aren't going to read documentation; they're just going to download Drupal, click install, and wonder why it's not working.

So, it looks like we should add something to install.txt (on the off chance someone might read it) -- it currently says nothing about PDO.

We should also change that error message so it says something about PDO, which is a UI text issue. So, adding a tag.

I added a note about PDO to the database section of http://drupal.org/requirements (pointing to lower down on the page for more details).

Given that there are quite a few other PHP config/extension requirements on that page, and none of them are currently mentioned in INSTALL.txt, I thought the best course of action there was to expand the paragraph suggesting people read the handbook, rather than adding PDO explicitly. New paragraph:

For more detailed information about Drupal requirements, including a list of
PHP extensions and configurations that are required, see "System requirements"
(http://drupal.org/requirements) in the Drupal handbook.

I also added PDO to the database error message. New message:

Your web server does not appear to support any common PDO database types. Check with your hosting provider to see if they support PDO (PHP Data Objects) and offer any databases that Drupal supports.

(the link there is to d.o/requirements also).

Here's a patch, covering these two changes to install.txt and install.php.

Looks good to me.

I like this, although it's only part of the solution. It's still a step forward.

I'm not sure if I'd say "PDO database types", or just "does not support any Drupal-supported database drivers", or something like that.

I thought that since the most common cause of seeing this was probably that PDO wasn't installed/enabled, mentioning PDO was useful. But we can definitely change it.

IMO, PDO should probably be handled over here as part of this issue: #641408: PHP extensions and PDO functionality should be checked at installation. (See the post-commit follow-ups.)

That sounds like a good plan, but until then should we still make this change?

Yes. Checking that PDO exists is a basic check for Drupal itself. Checking that we have a supported database available is part of the DB phase of the installer, and should be handled as gracefully as possible.

OK then. catch and I were happy with the current wording. Crell: Do you want it changed or should we RTBC this one?

IMO this should explicitly mention PDO. I've seen people come on irc with PDO and php5-mysql, but not PDO MySQL for whatever reason. So they have PDO support, and PHP support for MySQL, but they still get this message, and get very confused.

I'm happy enough with it. Let's do, then follow-up in the other issues.

Please see my notes/patch on #641408: PHP extensions and PDO functionality should be checked at installation.. I don't think we should be throwing an exceptioon on the settings page; we can catch it much earlier in system_requirements(). However the change in wording in install.txt is still usable. I attached a patch with only that change.

That is indeed a better place to do the PDO/database checking.

Committed #18 to CVS HEAD. This left out the exception stuff though.

Took a bit for me to figure this one out.
But you will need to do the following:

pecl install pdo
AND
pecl install pdo_mysql

Then restart your server.

Thanks, I've added the note above to the http://drupal.org/requirements page. If you have any further ideas for that page, please file a new issue.