This has been broken for me for months, but recently I found a fix. Using the Steam application, all you can do is browse your library. The store, community, forums etc; all don’t work. If you use Big Picture mode, everything is great. If you use a normal browser, everything is great.
Steam support gave up after a couple of suggestions. But after working through many possible fixes, I worked out what was wrong.
Here’s some of the other possible fixes I worked through first as these helped quite a few people (no one listed what worked for me so I assume it’s less likely to fix the problem!)
Clearing the Steam Web Browser Cache
Go to the Web Browser section of the Steam settings and delete the Cache and Cookies.
Disabling DirectWrite for font smoothing
Again within Steam settings, go to Interface and uncheck “Enable DirectWrite for improved font smoothing and kerning”
Clearing the htmlcache directory
Appdata may be a hidden folder so you may need to select the options to view hidden files in Explorer (under View in Windows 10).
Add Exceptions for Steam and SteamWebHelper
You might see errors in the event log about the firewall being unable to generate exceptions for the above two files;
You can manually create exceptions for those two files.
If that doesn’t work (and the errors persist) you can try copying the SteamWebHelper exe from a subfolder under \Steam\bin\cef to \Steam\bin.
Go to wherever your Steam is installed to try that.
Disable Chrome Embedded Framework Sandbox
This was originally listed to help get Steam working under WINE on Linux but apparently it works with Windows too. Create a short-cut to Steam with the “-no-cef-sandbox” switch, ie;
"C:\Program Files (x86)\Steam\Steam.exe" -no-cef-sandbox
Run Steam as an Administrator
Right-click on it and select “Run as Administrator”
What Worked For Me In the End
None of the above worked. I could use the normal web-browser but it made some things a bit of a pain (getting gift notifications, for example). Eventually I took the plunge and re-installed my PC.
It still was broken! Even though Steam was the first thing I installed!
Now I also knew I could login on another PC in the house and use Steam fine. That pointed at a hardware problem but I couldn’t work out what would stop web access on Steam only. The router must be ok (as it worked on other machines AND I could use a normal browser).
I couldn’t reliably reset the firewall exceptions (as above) so I thought it might be something to do with the permissions on the Steam folders. I normally have Steam installed to c:\games\Steam to keep it organised (and for another reason I’ll come to in a moment).
I re-installed Steam to the default location: Success!
To test I went back to the custom location; failure.
So that was it; something about the C:\Games\Steam folder. I hadn’t messed with any of the permissions there. But that I had done was mount a drive on c:\games\Steam. So instead of having a 2nd drive on D:\, I had it on c:\games\Steam so that Steam had the whole drive to play with.
This has been my config for years, though multiple systems and OS’s. So something changed in Windows or Steam a few months ago that stopped the firewall being able to correctly create exceptions on mounted drives.