Conquest of the Horde

I recently downloaded the great big single download client thingy, since my retail WoW is kept up to date. I changed the realmlist file, and nothing else. But when I try to run the application, I get the error:

Error 134
Failed to open required archive Data/wow-updatebase-15211.MPQ with error: 5

Wow.mfil download error: Failed to create file 'WoW.mfil Manigest is valid.

Is there any fix to this issue? I really, really don't want to download the entire thing again.

Are your retail WoW and CoTH WoW kept in separate places? I like(d) to keep my retail in the normal form and put the CoTH version in a zipped file.

Which OS are you using? If Windows 7, try moving the WoW folder out of Program Files. Put it anywhere else. Check to see if it's read-only (amend that if so), and ensure you're running wow.exe as an Administrator.

Make sure that the folder is not "read-only".

Thanks a bunch everyone, the file was set to read only. It's working just fine now, and I can connect to the server. ^-^