I've been getting this message a lot lately, too.
I think WCG's servers can't keep up with the load, though they seemed to get through OK during the tsunami created by the contribution of the Ripple Labs team earlier in the year (See Sekerob's recently-updated chart(s) eg here). Maybe there is some new bottleneck.
Or perhaps their card punches just can't keep up. Perhaps a Mr Hollerith at their host company might be able to help.

And it's working again. Seems to be happening quite frequently recently but doesn't seem to last for long thankfully.

How long this fundraiser site has been up is not clear, but wcg is getting a mention. As always, the members of standing are the last to know.

https://www.crowdrise.com/cureebola/fundraiser/scrippsresearchinsti

Drugs against these sites could represent powerful new treatments, but will require massive computational power to screen. Together, we can solve this. Dr. Saphire has partnered with IBM’s World Community Grid to find drugs through the Outsmart Ebola Together project. This humanitarian venture harnesses spare computing power from personal computers and mobile devices of over 680,000 volunteers around the world. When otherwise idle, this network of devices forms a virtual supercomputer that can dramatically accelerate her cutting-edge research. World Community Grid volunteers have already enabled important advances in AIDS, cancer, malaria, and dengue fever research.

Dr. Saphire needs to hire a postdoctoral fellow with computational experience to analyze the enormous volume of data generated by Outsmart Ebola Together volunteers and identify the most promising drug leads for further testing. Through the overwhelming support thus far to Dr. Saphire’s crowdfunding project, she has been able to purchase a key piece of equipment for her lab at The Scripps Research Institute in California that will enable her team to process the hundreds of samples currently arriving from around the world. Help her now hire a computational scientist to harness the World Community Grid data and develop much-needed drugs.

Together, we can find a cure for Ebola – help Dr. Saphire raise $175,000 toward her pivotal research by giving financially on the page, and sign up at worldcommunitygrid.org to donate the spare computing time from your personal computer, Android device, or Kindle Fire to Outsmart Ebola Together. When your computer is idle, it can join the global fight against Ebola.

Check in your BOINC Manager (Advanced View) Projects tab.
When you get the "can't open database" message, there will be a message that client communication is deferred for 60 min. A few of these delays in a row could cause you to run out of work.

You can force interruption of the timeout by clicking "Update", which will cause an immediate re-try.
If it's been 2 min since the last request for tasks, you might get some new work. Or you might get a "high load" message or another "can't open database".

Increasing your work cache might be an option.

[Some info from the WCG techs or a CA would be nice, but I guess they're all busy punching those data cards]
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[OT]: @lavaflow, re the OET project fundraiser - "... the members of standing are the last to know".
In the WCG News section: Help researchers find an Ebola cure
[/OT]