Unexpected Transport Error (Now Solved!)

[Hot 4 Myers]

Been having this problem for a few days now, one one day it was fine then the next, I get the "Unexpected Transport Error" message asking to restart Steam and restart Steam Webhelper. Neither worked of course, tried a few other things:

-Rebooting computer
-Reinstalling Steam and deleting cache folders
-Using cmd to reset TCP IP and flush DNS
-The fix I've read in the forums about suspending Steam in Resource Monitor while waiting for Webhelper to catch up
-Loading Steam on my Surface, logging out then logging back in on my desktop
-Contacted Steam support

None of the above worked and despite explaining in my ticket to support the things I've tried, I just got an unhelpful link to the troubleshooter the error message already linked me to. I'd like to avoid a complete reinstall of Steam (especially as I need a PC upgrade this year when Win 10 runs out anyway) especially because I'm not convinced it will solve the problem.

Update:

Thanks to Steam Support, I was able to solve the problem. I had a program called YouGov Pulse that was blocking Steam's access and uninstalling it (the program is being discontinued this month anyway) solved the problem. If you check the file "transport_client.txt" in (install directory)/Steam/logs, you'll see a line that looks something like this

"WebUITransport: Checked: 9128/17148"

The first number, in this case 9128, is the Process ID (PID under the details tab in Task Manager) of the program causing the problem. Checking it in Task Manager, you can find the problem and hopefully uninstall the program.

[shirl777]

I cannot help but this evening I cannot log into any game, I get the same error and tried those things to. Even disabled Nortons and firewall still doesnt work. And reinstalled Steam -

Worked well until tonight.

Steam encountered an unexpected error during startup (0x3000).

[Hot 4 Myers]

Originally posted by shirl777:

Steam encountered an unexpected error during startup (0x3000).

Yeah this is the same error code I'm having. I just have Windows own Firewall and Anti Virus and Steam is allowed through both. Hopefully if this problem becomes more widespread, support might be able to do something about it!

Edit: Found a solution in the following thread
https://steamcommunity.com/discussions/forum/1/592891465952144378/
Basically forcing Steam to downgrade to an earlier version and then making sure it doesn't auto update and I can launch again.

[shirl777]

thanks

[jiriky]

En ubuntu 24.04, pasa exactamente igual. H eprobado a desinstalarlo comletamente con remove --purge, en la version apt, he borrado directorios, todos. He reinstaldo steam con flatpack, snap incluso la version windows con crossover y todas la veces, el error aparece. Si fuerzo la instalación anterior, steam funciona, pero como ejecute steam de forma habitual, actualiza y vuelve al error. Espero que puedan arreglar el fallo, cada vez que falla el minidump se subre directamente a steam, a ver si analizandolo dan con el error.