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My Steam won't launch. It gives me an error - "Steam.exe (main exception): CMultifieldBlob(pSerialized) - Bad field". What does this mean and how do I fix it?

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up vote 6 down vote accepted

Just delete the clientregistry.blob in your Steam folder and nothing else, then launch Steam. Steam will just make a new clientregistry.blob.

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There is the rare problem when there's something else other than the clientregistry.blob is corrupted, but that's not the scope of this question. This is a more targeted (and faster) solution than mine. – Yuuki Oct 20 '12 at 20:23

SOURCE: How should I reset the ClientRegistry.blob when needed?

This error is caused by a corrupted ClientRegistry.blob file. Most likely, Steam closed incorrectly. Either your computer crashed or the Steam process was killed before Steam finishing writing to the file.

One way to fix this error is by going to your Steam folder (following are common default locations)

  • C:/Program Files/Steam on 32-bit Windows OS
  • C:/Program Files (x86)/Steam on 64-bit Windows OS
  • Users/[username]/Library/Application Support/Steam on Macs

For Windows OS, you'll want to delete everything EXCEPT steam.exe and the steamapps directory (this holds your game data). Then, restart Steam and you'll be fine.

For Mac OS, just delete everything in that directory and restart Steam.

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If it's a corrupted clientregistry.blob file, just delete that one file. Steam will happily recreate it on restart. It takes a little while, as it requires steam to scan for all your games, but it works fine. I do it quite often, whenever I'm restoring a game I've copied to a different hard drive. – Kexlox Jul 6 '12 at 4:31
@Kexlox Yeah, it makes sense but Steam recommends clearing the entire directory except for those things for god-knows-why. – Yuuki Jul 7 '12 at 3:06
@Yawus Do you have a source for that? – kalina Oct 19 '12 at 10:08
@pixel But deleting the ClientRegistry.blob has always lead to success for me. – fix_moeller Oct 20 '12 at 21:44

What I did was I went to the Steam site and clicked install. After I got the installer I clicked it and it said to restore corrupted files or to delete Steam. I clicked restore files and it worked perfectly for me.

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