Mysterious problem with MailMerge csv files solved (blocked data source files)

We have recently bumped into a weird problem – when we extracted patient data from Praktika for the MailMerge, Microsoft Word on some Windows machine was refusing to open the .CSV file with the extracted data.

After a lot of investigations and byte-to-byte file comparisons we have found that the culprit was the infamous Windows security. For some really unknown reason Microsoft Word refused to open the CSV file and the error message was ridiculously helpless – “Unable to find data source”.

If you right click on the CSV file you can see the following message: “The file came from another computer and might be blocked to help protect this computer.”



If you come across this problem, you have to click the Unblock button to allow MS Word to open this file or as a permanent solution, you have to add to the list of your Trusted sites.

Here you can find the instructions how to do this:


The permanent solution for this issue is to change Windows Trusted sites security option. You need to go to “Control Panel” -> “Internet Options” -> “Security” -> (Select the “Trusted Sites” zone) -> “Custom level”. Under “Miscellaneous” choose Enable for “Access data sources across domains”.

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