[Proposal] Increase minimum netframework target to net461

[iamcarbon]

.NET Framework 4.5.2, 4.6, 4.6.1 will reach End of Support on April 26, 2022 and will no longer be updated or receive security updates. Additionally, our dependencies (e.g. System.Security.Cryptography.Pkcs and System.Text.Encoding.CodePages) have already raised their minimum target to .NETFramework 4.6.1.

While there is currently little overhead maintaining support for these older targets, we're in an odd place if one of these libraries requires a patch and we are unable to update.

Users that are unable to upgrade running Windows Server 2013 can continue to utilize the current library release.

[ ] https://devblogs.microsoft.com/dotnet/net-framework-4-5-2-4-6-4-6-1-will-reach-end-of-support-on-april-26-2022/

[iamcarbon]

We should also consider dropping our .NET5.0 target to keep things simple and prevent our framework targets from pilling up now that .NET is on a yearly release cycle. .NET5.0 users would continue to be supported through the .NETSTANDARD2.1 target.

.NET 5.0 will reach end of life on May 08, 2022 and will receive no future updates, while .NET6.0 is supported for 3 years.

[jstedfast]

I've been considering dropping 4.5.2 and bumping the 4.6 version to 4.6.1 because that actually gets us the CodePages feature.

I wish I had metrics on how many users were still on various frameworks. I've been periodically purging old frameworks. For example, with 3.0, I dropped support for netstandard1.x and then recently dropped support for net45 (bumped to net452). Dropped support for net35 and net40 for MimeKit 2.0 which was years after 4.0 was end-of-lifed.

I think what I'll do is to continue making releases for these frameworks until the end of April - I think that's a good time to drop them (and we'd have the perfect excuse).

I mostly dropped net45 recently because I switched to VS2022 when I moved to the VS team and I no longer had the net45 targeting pack available so had no choice.

(Now that I have multiple copies of VS2022 installed, I don't have room for VS2019 haha)

[jstedfast]

I just dropped net46 in favor of net461. I do know I have some users on net461 based on bug reports I've gotten in the past month or so around TypeLoadExceptions due to missing System.Text.Encoding.CodePages.

...which leads me to wonder if I should make all .NET Framework versions >= 461 depend on System.Text.Encoding.CodePages rather than just using System.Reflection to dynamically load it if it exists. I hate using reflection hacks like that...

[iamcarbon]

+1 to removing the reflection hack and taking a dependency on System.Text.Encoding.CodePages.

[jstedfast]

Just added the System.Text.Encoding.CodePages dependency. I think this will solve all of the "it doesn't work on ASP.NET" error reports I always get :)

[jstedfast]

Lifecycle: https://docs.microsoft.com/en-us/lifecycle/products/microsoft-net-framework