dotnet/maui · error · BuildException

XC0007

XC0007

Error message

Enum value not found for "{0}".

What it means

Thrown after the XAML compiler iterates every field of the target enum and none matches the trimmed value(s) supplied in the attribute. The `found` flag stays false, meaning the literal name written in XAML does not exist as a member of the resolved enum type.

Source

Thrown at src/Controls/src/Build.Tasks/NodeILExtensions.cs:407

								i |= (int)field.Constant;
								break;
							case "System.UInt32":
								ui |= (uint)field.Constant;
								break;
							case "System.Int64":
								l |= (long)field.Constant;
								break;
							case "System.UInt64":
								ul |= (ulong)field.Constant;
								break;
						}
						found = true;
					}
				}
			}

			if (!found)
				throw new BuildException(BuildExceptionCode.EnumValueMissing, lineInfo, null, value);

			switch (typeRef.FullName)
			{
				case "System.Byte":
					return Create(Ldc_I4, (int)b);
				case "System.SByte":
					return Create(Ldc_I4, (int)sb);
				case "System.Int16":
					return Create(Ldc_I4, (int)s);
				case "System.UInt16":
					return Create(Ldc_I4, (int)us);
				case "System.Int32":
					return Create(Ldc_I4, (int)i);
				case "System.UInt32":
					return Create(Ldc_I4, (uint)ui);
				case "System.Int64":
					return Create(Ldc_I4, (long)l);
				case "System.UInt64":

View on GitHub (pinned to f377ff1c5e)

Solutions

1. Verify the exact enum member name (names are case-sensitive).
2. Confirm which enum type the property actually expects and that the correct assembly/namespace is referenced.
3. Rebuild the project referencing the assembly that defines the enum so the compiler sees the current members.

Example fix

<!-- before -->
<StackLayout Orientation="Horz" />

<!-- after -->
<StackLayout Orientation="Horizontal" />

// Verify the value is a defined member name (case-sensitive) of the expected enum
static bool IsDefinedEnumName(Type enumType, string xamlValue)
    => xamlValue.Split(',').Select(v => v.Trim())
        .All(v => Enum.GetNames(enumType).Contains(v));

static bool IsValidEnumValue<T>(string value) where T : struct, Enum
    => value.Split(',').Select(v => v.Trim()).All(v => Enum.IsDefined(typeof(T), v));

When it happens

Trigger: An attribute resolves to an enum but the value string (after split-on-comma and trim) matches no field name on that enum, e.g. `Orientation="Horz"` where the enum defines `Horizontal`.

Common situations: Typo in an enum member name; the member was renamed or removed in a newer package version; the wrong enum type was resolved due to a namespace/assembly mismatch.

Related errors

• XC0040
• XC0063
• XC0044
• XC0020
• XC0040

AI-assisted analysis of dotnet/maui@f377ff1c5e (2026-08-13). Data as JSON: /api/errors/0552051952fde502. Report an issue: GitHub.