URI paths on Unix

docs/core/compatibility/3.1-5.0.md

@@ -122,6 +122,7 @@ If you're migrating from version 3.1 of .NET Core, ASP.NET Core, or EF Core to v
 
 ## Core .NET libraries
 
+- [URI paths with non-ASCII characters parse correctly on Unix](#uri-paths-with-non-ascii-characters-parse-correctly-on-unix)
 - [Uri recognition of UNC paths on Unix](#uri-recognition-of-unc-paths-on-unix)
 - [Environment.OSVersion returns the correct operating system version](#environmentosversion-returns-the-correct-operating-system-version)
 - [Complexity of LINQ OrderBy.First{OrDefault} increased](#complexity-of-linq-orderbyfirstordefault-increased)
@@ -136,6 +137,10 @@ If you're migrating from version 3.1 of .NET Core, ASP.NET Core, or EF Core to v
 - [CounterSet.CreateCounterSetInstance now throws InvalidOperationException if instance already exist](#countersetcreatecountersetinstance-now-throws-invalidoperationexception-if-instance-already-exists)
 - [Microsoft.DotNet.PlatformAbstractions package removed](#microsoftdotnetplatformabstractions-package-removed)
 
+[!INCLUDE [non-ascii-chars-in-uri-parsed-correctly](../../../includes/core-changes/corefx/5.0/non-ascii-chars-in-uri-parsed-correctly.md)]
+
+***
+
 [!INCLUDE [unc-path-recognition-unix](../../../includes/core-changes/corefx/5.0/unc-path-recognition-unix.md)]
 
 ***

docs/core/compatibility/corefx.md

@@ -11,6 +11,7 @@ The following breaking changes are documented on this page:
 
 | Breaking change | Version introduced |
 | - | :-: |
+| [URI paths with non-ASCII characters parse correctly on Unix](#uri-paths-with-non-ascii-characters-parse-correctly-on-unix) | 5.0 |
 | [Uri recognition of UNC paths on Unix](#uri-recognition-of-unc-paths-on-unix) | 5.0 |
 | [Environment.OSVersion returns the correct operating system version](#environmentosversion-returns-the-correct-operating-system-version) | 5.0 |
 | [Complexity of LINQ OrderBy.First{OrDefault} increased](#complexity-of-linq-orderbyfirstordefault-increased) | 5.0 |
@@ -43,6 +44,10 @@ The following breaking changes are documented on this page:
 
 ## .NET 5.0
 
+[!INCLUDE [non-ascii-chars-in-uri-parsed-correctly](../../../includes/core-changes/corefx/5.0/non-ascii-chars-in-uri-parsed-correctly.md)]
+
+***
+
 [!INCLUDE [unc-path-recognition-unix](../../../includes/core-changes/corefx/5.0/unc-path-recognition-unix.md)]
 
 ***

includes/core-changes/corefx/5.0/non-ascii-chars-in-uri-parsed-correctly.md

@@ -0,0 +1,54 @@
+### URI paths with non-ASCII characters parse correctly on Unix
+
+A bug was fixed in the <xref:System.Uri?displayProperty=fullName> class such that absolute URI paths that contain non-ASCII characters now parse correctly on Unix platforms.
+
+#### Change description
+
+In previous versions of .NET, absolute URI paths that contain non-ASCII characters are parsed incorrectly on Unix platforms, and segments of the path are duplicated. (Absolute paths are those that start with "/".) The parsing issue has been fixed for .NET 5.0. If you move from a previous version of .NET to .NET 5.0 or later, you'll get different values produced by <xref:System.Uri.AbsoluteUri?displayProperty=nameWithType>, <xref:System.Uri.ToString?displayProperty=nameWithType>, and other <xref:System.Uri> members.
+
+Consider the output of the following code when run on Unix.
+
+```csharp
+var myUri = new Uri("/üri");
+
+Console.WriteLine($"AbsoluteUri: {myUri.AbsoluteUri}");
+Console.WriteLine($"ToString: {myUri.ToString()}");
+```
+
+Output on previous .NET version:
+
+```text
+AbsoluteUri: /%C3%BCri/%C3%BCri
+ToString: /üri/üri
+```
+
+Output on .NET 5.0 or later version:
+
+```text
+AbsoluteUri: /%C3%BCri
+ToString: /üri
+```
+
+#### Version introduced
+
+5.0
+
+#### Recommended action
+
+If you have code that expects and accounts for the duplicated path segments, you can remove that code.
+
+#### Category
+
+Core .NET libraries
+
+#### Affected APIs
+
+- <xref:System.Uri?displayProperty=fullName>
+
+<!--
+
+#### Affected APIs
+
+- `T:System.Uri`
+
+-->