If this error is displayed while you are trying to install the HEIMDAL Agent it means that there is a problem with the .NET Framework version on your computer. In order to fix this issue there are two steps that you need to complete:
1. Download .NET Framework 4.6.1 from here and install it on the machine you want to install HEIMDAL Agent: https://www.microsoft.com/en-us/download/details.aspx?id=49982
2. After step 1 is completed, try to install the HEIMDAL Agent and see if it works. It may be possible that you will get an error when you will try to install .NET Framework 4.6.1 in which you will be announced that this version of .NET Framework is already installed. If that happens, download the .NET Repair Tool from here and run it on your PC: https://support.microsoft.com/en-us/kb/2698555
After these two steps are completed, try to reinstall the HEIMDAL Agent, the installation should work fine now. If, for any reason, the installation still doesn’t work, please contact our Support Team using the contact form.