BREAKING CHANGE: Changed default behavior of ShellItem.Properties so that it is read-only. It was failing for all shell items that didn't have their own properties. To get previous behavior, simply set "shellItem.Properties.ReadOnly = false" before setting properties.

UnitTests/Windows.Shell/ShellItemPropStoreTests.cs

@@ -3,6 +3,9 @@ using System;
 using System.Collections;
 using System.Diagnostics;
 using System.Linq;
+using System.Runtime.InteropServices;
+using Vanara.PInvoke.Tests;
+using static Vanara.PInvoke.Ole32;
 
 namespace Vanara.Windows.Shell.Tests
 {
@@ -14,9 +17,9 @@ namespace Vanara.Windows.Shell.Tests
 		[Test]
 		public void DescriptionTest()
 		{
-			using var i = new ShellItem(testDoc);
+			using var i = new ShellItem(TestCaseSources.LogFile);
 			var c = 0;
-			foreach (var d in i.Properties.Descriptions)
+			foreach (var d in i.PropertyDescriptions)
 			{
 				c++;
 				Assert.That(d, Is.Not.Null);
@@ -75,6 +78,22 @@ namespace Vanara.Windows.Shell.Tests
 			Assert.That(c, Is.EqualTo(i.Properties.Count));
 		}
 
+		[Test]
+		public void WritableTest()
+		{
+			// Try accessing a text file's writable properties and assert a failure.
+			using (var i = new ShellItem(TestCaseSources.LogFile))
+			{
+				i.Properties.ReadOnly = false;
+				Assert.That(() => i.Properties.TryGetValue(PROPERTYKEY.System.Size, out var val), Throws.TypeOf<InvalidOperationException>());
+			}
+
+			// Try accessing a Word file's writable properties and assert successs.
+			using var w = new ShellItem(testDoc);
+			w.Properties.ReadOnly = false;
+			Assert.That(w.Properties.TryGetValue(PROPERTYKEY.System.Size, out _), Is.True);
+		}
+
 		[Test]
 		public void ShellItemPropertyStoreTest1()
 		{

Windows.Shell/ShellObjects/ShellItem.cs

@@ -6,7 +6,6 @@ using System.Drawing;
 using System.Runtime.InteropServices;
 using System.Runtime.InteropServices.ComTypes;
 using System.Text;
-using System.Threading;
 using Vanara.Extensions;
 using Vanara.InteropServices;
 using Vanara.PInvoke;
@@ -458,13 +457,21 @@ namespace Vanara.Windows.Shell
 			}
 		}
 
-		/// <summary>Gets the property store for the item.</summary>
+		/// <summary>
+		/// <para>Gets the property store for the item.</para>
+		/// <note>Initially, this property store is the read-only store (change from R/W in v3.2.9) and should always have properties.
+		/// However, setting any of the properties of this value change the function of all subsequent uses. For example, if you set the
+		/// <see cref="ShellItemPropertyStore.ReadOnly"/> value to <see langword="false"/>, all subsequent calls to <see
+		/// cref="ShellItem.Properties"/> will access the read-write property store. If this <see cref="ShellItem"/> does not support
+		/// properties directly, your use of this property will fail. It is important that you check for exceptions when changing the
+		/// properties of this value to prevent unexpected failures.</note>
+		/// </summary>
 		/// <value>The dictionary of properties.</value>
-		public ShellItemPropertyStore Properties => props ?? (props = new ShellItemPropertyStore(this) { ReadOnly = false });
+		public ShellItemPropertyStore Properties => props ??= new ShellItemPropertyStore(this);
 
-		/// <summary>Gets a property description list object containing descriptions of all properties.</summary>
+		/// <summary>Gets a property description list object containing descriptions of all properties suitable to be shown in the UI.</summary>
 		/// <returns>A complete <see cref="PropertyDescriptionList"/> instance.</returns>
-		public PropertyDescriptionList PropertyDescriptions => propDescList ?? (propDescList = GetPropertyDescriptionList(PROPERTYKEY.System.PropList.FullDetails));
+		public PropertyDescriptionList PropertyDescriptions => propDescList ??= GetPropertyDescriptionList(PROPERTYKEY.System.PropList.FullDetails);
 
 		/// <summary>Gets the normal tool tip text associated with this item.</summary>
 		/// <value>The tool tip text.</value>

Windows.Shell/Vanara.Windows.Shell.csproj

@@ -17,6 +17,7 @@ Enumerations
 ChangeFilters, ExecutableType, FolderItemFilter, LibraryFolderFilter, LibraryViewTemplate, LinkResolution, OperationFlags, ShellIconType, ShellImageSize, ShellItemAttribute, ShellItemComparison, ShellItemDisplayString, ShellItemGetImageOptions, ShellItemToolTipOptions, TaskbarButtonProgressState, TaskbarItemTabThumbnailOption, TransferFlags, VerbMultiSelectModel, VerbPosition, VerbSelectionModel, Visibility
 
 </PackageReleaseNotes>
+    <RootNamespace>Vanara.Windows.Shell</RootNamespace>
   </PropertyGroup>
   <ItemGroup>
     <Compile Remove="_InProgress_\**\*" />