Latest Microsoft security patch for Windows Server causing issues in Build DataTable DataType


I have a XAML which has a Build DataTable activity. One of the columns in the Build DataTable is of DataType System.Net.Mail.MailMessage. It was working fine until yesterday after which my Windows Server 2016 was recently updated with the Microsoft security patch (KB4565511 & KB4565912)

After this patch update it is not working anymore. The same code in another server without this patch is working as expected. Can anyone try the same? Will there be any update to the package to fix this issue?

Error message - “Type System.Net.Mail.MailMessage, System Version=, is not allowed here. See

Please let me know if you need any more details.


@loginerror, @Palaniyappan, @ppr please on this

we can confirm that there was a change and this type of DataType is not longer allowed. Let us know what is handled and what is targeted. In some cases it can be changed to:

  • storing the mails on filesystem
  • handling the filepath to it in the datatable

But as mentioned lets start with your summary of the requirements


HI @ppr, thanks for your response and confirmation. I am having this data table with a column type as MailMessage to send response to the email once they are processed. I am thinking like we can do some work around like having a dictionary collection of emails with incremental values as key and have the key to replace the column with MailMessage datatype.

But I am checking to see whether a solution is possible without a code change as I might end up changing a lot of files plus a lot of effort. Is there a possibility of any updates to these activities from UIPath or any other suggestions so that I can do this without code changes?

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build datatable (add datacolumn?) are blocked due the serialisation as described in the Microsoft link.

Give a try to add a datacolumn of mail message / interacting with the column by using the invoke code acitivity

Thanks @ppr. I am assuming that there is no way to avoid code changes at this point. I will try your suggestion and will update

Just wanted to update - we are aware of this issue and our team is evaluating the impact of this change across all our official packages.

A fix to the System activity package is already scheduled for the next Community Release.

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Thank you @loginerror That would be great. Thanks for the update

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