Conflict with server security (digital signature not OK)

Hi, everyone.

I’ve installed Keyman on all three of my work computers (one at each of my three workplaces), but at one of my workplaces, I am unable to start Keyman due to conflict with server security.

When I try to start Keyman, I get the error that “The introduction was returned by the server” (or something like that - I am translating from Japanese, as I am using a Japanese computer, so what it would say on an English computer may differ considerably, but I hope that gives you a lead).

No one at said workplace is able to solve this problem.

As per the Help manual, I right-clicked on keyman23.dll, opened Properties, selected the Digital Signature tab and looked at the details of the digital signatures on the list.

Instead of the message “This digital signature is OK”, I saw “Unable to verify signature credentials” (again, a technologically-uninformed translation from Japanese).

Could you please tell me how to solve this problem?

Many thanks,


This can happen for one of two reasons:

  1. The file has been corrupted, so the digital signature is therefore not valid.
  2. The root certificates on the computer are out of date and missing the root certificate against which the Keyman app is signed.

The process to update root certificates varies according to the version of Windows. The following references may help for offline computers: and

Thank you very much for your reply!

It will be a few weeks before I use that computer again (summer holidays and all), but when I do, I’ll try it out and get back to you on the results!