/usr/bin/pdbedit failed :
Unable to modify TDB passwd ! Error: Record exists
occured while storing the RID index (RID_000007da)
Probably, you have changed samba root account manually with 'smbpasswd'
Obviously I'm missing something, but I don't know what it is. I could probably just create the web with a different user, but I could see that leading to problems with orphaned users left lying about.
You can try to create the web with a user mtexas once again.