Symptom

After installing or updating to PTV Routeoptimser 2026_1, the Web API stopped working.

Cause

The DLL in the client folder is newer than expected.

Resolution

As this is a configuration issue, it cannot be fixed in ROST 2026 via a general patch.
 

Users must add the following entry to the assemblyBinding section to resolve it.

 “SmarTourService.WindowsServiceHost.exe” and, if necessary, to “SmarTourService.ConsoleHost.exe.config.”

<dependentAssembly>
        <assemblyIdentity name="Microsoft.Owin" publicKeyToken="31bf3856ad364e35" culture="neutral"/>
        <bindingRedirect oldVersion="0.0.0.0-4.2.3.0" newVersion="4.2.3.0"/>
 </dependentAssembly> 

The entry has been added to the new trunk, meaning the next ROST version.

We created a PowerShell script to fix this:

Run it with: powershell -ExecutionPolicy Bypass -File "Add-OwinBindingRedirect.ps1"
Find the script in the client folder; Patch 2 or later is needed