Resolving License Acquisition Errors

Learn how to resolve common issues with automatic license acquisition for Time Tagger software.

TimeTaggerVirtual allows you to perform measurements using the Time Tagger library with time-tag dump file(s) as a data source instead of Time Tagger hardware. Replaying recorded time-tag stream dumps this way, without having the Time Tagger connected to the host PC, requires a software license.

As explained in the installation section of our documentation, this license is acquired automatically the first time a Time Tagger hardware instance is created (e.g. via the createTimeTagger function, or by launching Time Tagger Lab) with the hardware connected to the PC and an active internet connection, and it is tied to that specific machine.

Sometimes, this license generation fails. This can be due to:

• the absence of a stable Internet connection, or a firewall blocking the license request
• the default application data folder not being writable by the current user

Usually, you will notice a failed license request when error messages appear, as shown below:

HostLicense.cpp:355: Downloading the host license failed with HTTP status 500.
HostLicense.cpp:475: License downloading yielded an empty request.
HostLicense.cpp:483: Invalid license downloaded.
HostLicense.cpp:379: Empty license file found.
HostLicense.cpp:654: Validating the license failed. Please recreate the license.

If the default application data folder is not writable, note that it can be configured to point to a different location.

What if the Time Tagger hardware cannot be connected to this PC at all, so the license can never be generated automatically? There are two other options for acquiring the license:

1. Generate the license request offline. Run the following executable from a command line terminal:

   • C:\Program Files\Swabian Instruments\Time Tagger\driver\x64\LicenseRequestGenerator.exe on Windows
   • or "/usr/lib/timetagger/x64/LicenseRequestGenerator" on Linux

   You will be asked to enter your full name and email. This generates a LicenseRequest.txt file in the application data folder, by default "%APPDATA%\Swabian Instruments\Time Tagger" on Windows or "$HOME/.timetagger" on Linux. This default location can be changed by setting the TIMETAGGER_CONFIG_DIR environment variable to a custom path before running the generator or the Time Tagger software.

   Please double-check that the LicenseRequest.txt file was created in that folder, then send it to the Support Team (support@swabianinstruments.com). We will reply with a signed License.txt file, which needs to be placed in the same application data folder as the LicenseRequest.txt file (again, the default path unless you configured a custom one via TIMETAGGER_CONFIG_DIR).

2. As a workaround, use the TimeTaggerNetwork class instead. Start the Time Tagger server from a PC the Time Tagger is connected to. With the call of createTimeTaggerNetwork in the client (second PC), the software license is transferred to it. You can close the connection/instance now and start an instance of TimeTaggerVirtual on this second PC. For the procedure, please find the server and client Python scripts in our installation folder. The default locations are:

   • “C:\Program Files\Swabian Instruments\Time Tagger\examples\python\8-NetworkTimeTagger” for Windows
   • "/usr/lib/timetagger/examples/python/8-NetworkTimeTagger" for Linux

Once the license acquisition succeeds, no further requests will be made.