Mdtool 出现Add-in scan operation failed

运行mdtool出现错误:
Add-in scan operation failed.
ERROR: The add-in database could not be updated. It may be due to file corruption. Try running the setup repair utility

这个是由于安装Unity在网络盘造成的问题，

.net 4.0之后，需要在mdtool.exe.config加入:

<runtime>
....
      <loadFromRemoteSources enabled="true"/>

</runtime>