Build errors with .NET 3.1

[martinboers]

When attempting to build the CLI from source using .NET Core 3.1 (as advised in the README), the command dotnet build src -p:PlcNextToolName=plcncli results in the following error:

/usr/share/dotnet/sdk/3.1.425/Microsoft.Common.CurrentVersion.targets(1177,5): error MSB3971: The reference assemblies for ".NETFramework,Version=v6.0" were not found. You might be using an older .NET SDK to target .NET 5.0 or higher. Update Visual Studio and/or your .NET SDK. [/home/m/Projects/PLCnext_CLI/src/PlcNext/PlcNext.csproj]
/usr/share/dotnet/sdk/3.1.425/Microsoft.Common.CurrentVersion.targets(1177,5): error MSB3971: The reference assemblies for ".NETFramework,Version=v6.0" were not found. You might be using an older .NET SDK to target .NET 5.0 or higher. Update Visual Studio and/or your .NET SDK. [/home/m/Projects/PLCnext_CLI/src/Test.PlcNext/Test.PlcNext.csproj]
Deploy/AppDeployEngine.cs(24,32): error CS1514: { expected [/home/m/Projects/PLCnext_CLI/src/PlcNext.Common/PlcNext.Common.csproj]
Build/NoBuildEngine.cs(17,31): error CS1514: { expected [/home/m/Projects/PLCnext_CLI/src/PlcNext.Common/PlcNext.Common.csproj]
Generate/NoGenerateEngine.cs(20,34): error CS1514: { expected [/home/m/Projects/PLCnext_CLI/src/PlcNext.Common/PlcNext.Common.csproj]
Deploy/AppDeployEngine.cs(124,2): error CS1513: } expected [/home/m/Projects/PLCnext_CLI/src/PlcNext.Common/PlcNext.Common.csproj]
Build/NoBuildEngine.cs(33,2): error CS1513: } expected [/home/m/Projects/PLCnext_CLI/src/PlcNext.Common/PlcNext.Common.csproj]
Generate/NoGenerateEngine.cs(41,2): error CS1513: } expected /usr/share/dotnet/sdk/3.1.425/Microsoft.Common.CurrentVersion.targets(1177,5): error MSB3971: The reference assemblies for ".NETFramework,Version=v6.0" were not found. You might be using an older .NET SDK to target .NET 5.0 or higher. Update Visual Studio and/or your .NET SDK. [/home/m/Projects/PLCnext_CLI/src/PlcNext/PlcNext.csproj]
/usr/share/dotnet/sdk/3.1.425/Microsoft.Common.CurrentVersion.targets(1177,5): error MSB3971: The reference assemblies for ".NETFramework,Version=v6.0" were not found. You might be using an older .NET SDK to target .NET 5.0 or higher. Update Visual Studio and/or your .NET SDK. [/home/m/Projects/PLCnext_CLI/src/Test.PlcNext/Test.PlcNext.csproj]
Deploy/AppDeployEngine.cs(24,32): error CS1514: { expected [/home/m/Projects/PLCnext_CLI/src/PlcNext.Common/PlcNext.Common.csproj]
Build/NoBuildEngine.cs(17,31): error CS1514: { expected [/home/m/Projects/PLCnext_CLI/src/PlcNext.Common/PlcNext.Common.csproj]
Generate/NoGenerateEngine.cs(20,34): error CS1514: { expected [/home/m/Projects/PLCnext_CLI/src/PlcNext.Common/PlcNext.Common.csproj]
Deploy/AppDeployEngine.cs(124,2): error CS1513: } expected [/home/m/Projects/PLCnext_CLI/src/PlcNext.Common/PlcNext.Common.csproj]
Build/NoBuildEngine.cs(33,2): error CS1513: } expected [/home/m/Projects/PLCnext_CLI/src/PlcNext.Common/PlcNext.Common.csproj]
Generate/NoGenerateEngine.cs(41,2): error CS1513: } expected [/home/m/Projects/PLCnext_CLI/src/PlcNext.Common/PlcNext.Common.csproj]
[/home/m/Projects/PLCnext_CLI/src/PlcNext.Common/PlcNext.Common.csproj]

When dotnet-sdk-7.0 is installed instead of dotnet-sdk-3.1, these errors do not appear.

[mluhmann]

Ticket no. 4700
Fixed with release 2024.0. The toolchain moved to .NET 7 and the readme will be adapted