This document lists known issues for **.NET 5 Preview 1 and beyond releases** which may be encountered during usage.
## .NET Runtime
### Preview 1
1. Certain regular expressions involving negated character classes may fail to match correctly. This was a regression that occurred during extensive performance improvements made to the regular expression engine in 5.0. There is no general workaround, but modifying the expression may avoid the problem. This will be fixed in Preview 2. The issue [dotnet/runtime #33399](https://github.com/dotnet/runtime/issues/33399) explains the bug in detail.
2. Stepping with the debugger into code in certain assemblies in the .NET Platform may not succeed. This is because the assemblies do not have correct SourceLink information. This will be fixed in Preview 2. It is tracked by [dotnet/runtime #33097](https://github.com/dotnet/runtime/issues/33097).
3. The Microsoft.Windows.Compatibility package references dependencies that are not available at the targeted versions. To workaround, individually reference the packages your project needs. It is tracked by [dotnet/runtime/issues #34351](https://github.com/dotnet/runtime/issues/34351)
### Preview 2
1. The Microsoft.Windows.Compatibility package references dependencies that are not available at the targeted versions. To workaround, individually reference the packages your project needs. It is tracked by [dotnet/runtime/issues #34351](https://github.com/dotnet/runtime/issues/34351)
1. Runtime-dependent deployments of apps targeting .NET Core 3.1 that are created with .NET Core SDK 5.0.100 Preview 1 will require version 3.1.2 of the .NET Core runtime. This issue is tracked by [dotnet/sdk #10812](https://github.com/dotnet/sdk/issues/10812)