bump as I've same problem...

I never used windows 10 but I'd check if everything ok with access to storage folder/files
Should be in C:\ProgramData\GOG.com\Galaxy\storage
if not, try storagePath in registry
HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\GOG.com\GalaxyClient\settings
key for exact value.

I'm now experiencing this very same issue but on Win8 64-bit.
Far as I can tell the registry keys are fine, what exactly am I looking for in the ProgramData folder?
I can access GOG.com\Galaxy\storage fine, am I meant to look for something specific therein?

Check if you have read and write permissions. Try running Galaxy with administrator rights.
Also make sure files aren't locked with antivirus/firewall..

Thank you. Unfortunately the problem continues to persist.
I do have read/write permits, running it as admin doesn't change the result and my antivirus & firewall both are set to allow Galaxy.
It's not a major issue though, given that I can still directly download games and play them.

Could you please report the issue at http://mantis.gog.com/ with logs (%ALLUSERSPROFILE%\GOG.com\Galaxy\logs\) attached?

Galaxy did run once after "upgrading" (new drivers only available for w10 so i had no alternative to fix a driver related problem).

Atfer reinstalling it only run once again scanning stuff, later after another shutdown the same issue again, i reported with the logs zipped as suggested

if i read the logs right it seems that galaxy cant retrieve the key from the registry?

I checked your logs and it looks to me like galaxy is looking for a 32-bit registry keys on a 64-bit systems for some reason..
Temporary fix, which may or may not work would be exporting
HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\GOG.com\GalaxyClient\
key and importing again without Wow6432Node\ parts.
HKEY_LOCAL_MACHINE\SOFTWARE\GOG.com\GalaxyClient\

Try it only if you know what you're doing ; )

edit:
I just logged to windows (what a strange feeling, hell I think I'll play the witcher a bit) and as I thought there is no HKEY_LOCAL_MACHINE\SOFTWARE\GOG.com\GalaxyClient\
key on a 64-bit windows 7.. I don't think my 'fix' can be harmful, but not going to takeany responsibility if soemthing goes wrong, as awlays ; )

I'm suddenly running into the same issue here.

Here's a link to today's GalaxyClient.log:
http://pastebin.com/XLe6YkQR

Any help would be appreciated

Please, log in to http://mantis.gog.com with your gog credentials and fill out report.

Hi Mike, I added my information to an existing ticket.
#0004097

I'm unable to use the client at all :(

Having the same issue, has there been any responce from CD Projekt? I dearly hope that they fix this before Blood and Wine comes out.

I've got some great news! You may still enjoy your games : )
I'm pretty sure problem will be resolved soon.

Why? Has internet browser downloads stopped working? Net has been around a lot longer than crappy clientware.