Steam encountered an unexpected error during startup (0x3000)

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spyderDFX 23 Mar @ 2:30pm

Hi. So, after some March update, I'm getting this error on startup.

I can rollback to an older version using those steps https://gtm.steamproxy.vip/discussions/forum/1/592891465952144378/#c592891465952179735
and the older version works fine.
But I'm afraid that using this older version can cause some issues with games.

Steam\logs\webhelper.txt says:
SP Shared JS Context-'SharedJSCo': WARNING: https://steamloopback.host/library.js:2: websocket error
SP Shared JS Context-'SharedJSCo': WARNING: https://steamloopback.host/library.js:2: websocket error
SP Shared JS Context-'SharedJSCo': WARNING: https://steamloopback.host/library.js:2: failed to reach open state
SP Shared JS Context-'SharedJSCo': WARNING: https://steamloopback.host/library.js:2: connect attempt failed: 2 - failed to reach open state

I added Steam Client WebHelper to firewall exceptions, I tried to reset net interfaces via "netsh int ip reset" command - nothing helped

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Showing 1-8 of 8 comments

Herr Handtralla 29 Mar @ 4:04am

Same

spyderDFX 31 Mar @ 5:50am

I managed to get rid of this error by allowing absolutely ALL connections for steam and webhelper processes. Not sure if this is expected behavior. Steam supposed to work with OutgoingOnly

FastSlowGrey 7 Apr @ 6:18pm

Originally posted by spyderDFX:
I managed to get rid of this error by allowing absolutely ALL connections for steam and webhelper processes. Not sure if this is expected behavior. Steam supposed to work with OutgoingOnly

Hi, which specific settings did you end up changing?

gls1 9 Apr @ 10:39am

I also had the 0x3000 error. For me, for unknown reasons (possibly a program not cleaning up after itself?) the system was set up to use a local proxy. Settings -> Network and Internet -> Proxy -> turn off manual proxy.

Ragnar Ironhide 7 May @ 7:04pm

Well, ChatGPT fixed this issue for me real fast. Go to your steam folder->steamapps then delete the entire shadercache folder then run steam.

savexu 16 Aug @ 11:21pm

Originally posted by gls1:
I also had the 0x3000 error. For me, for unknown reasons (possibly a program not cleaning up after itself?) the system was set up to use a local proxy. Settings -> Network and Internet -> Proxy -> turn off manual proxy.

This helped me, it was all due to proxies from Fiddler

Not a Human 19 Aug @ 4:19pm

If you've encountered this issue, this solution should help (it worked for me).

First, clear the entire shadercache and appcache folders in the main Steam directory. Then, check if you're using custom DNS servers or a proxy—if so, temporarily disable them. For example, I use AdGuard for Windows, and once I disabled it, Steam started working properly and was no longer blocked at startup.

I hope this helps someone! <3