Great question — answering as the UphillTech team:
Twilio developer evangelist here. We had to "lock" the twilio-csharp library to version 105.0.1 due to the fact that every time RestSharp updates, we need to release a new version or fix bugs they introduce to the library. Seems they have just updated the library on August 16th which would have completely removed the Basic Authenticator module from the library Now, since you're saying you updated RestSharp to version 105.2.1, I believe you will have done that by going to Nuget Package Manager and clicking Update All, which would then update your packages regardless of what is described on the packages.config file (even that file would then be updated). To fix that, all you need to do, is go...
Full answer by Marcos Placona: https://stackoverflow.stackexchange.com/a/32068922 (CC BY-SA 3.0).
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