unoplatform/uno · error · ArgumentException

Member '{0}' could not be resolved to a static member

Error message

Member '{0}' could not be resolved to a static member

What it means

Thrown by StaticExtension when Member was supplied and MemberType was set, but neither a public static property nor a public static field with that Member name exists on MemberType. The lookup uses BindingFlags.Public | BindingFlags.Static, so non-public, instance-only, or misspelled members will not be found.

Source

Thrown at src/SourceGenerators/System.Xaml/System.Windows.Markup/StaticExtension.cs:77

			}

			if (MemberType != null) {
				var pi = MemberType.GetProperty (Member, BindingFlags.Public | BindingFlags.Static);
				if (pi != null)
				{
					return pi.GetValue (null, null);
				}

				var fi = MemberType.GetField (Member, BindingFlags.Public | BindingFlags.Static);
				if (fi != null)
				{
					return fi.GetValue (null);
				}
			}
			// there might be some cases that it could still
			// resolve a static member without MemberType, 
			// but we don't know any of such so far.
			throw new ArgumentException (String.Format (CultureInfo.InvariantCulture, "Member '{0}' could not be resolved to a static member", Member));
		}
	}
}

View on GitHub (pinned to 0418340488)

Solutions

1. Verify the member exists as a public static field or property on MemberType using reflection or an IDE go-to-definition.
2. Correct spelling and casing of Member to match the declared identifier exactly.
3. If the member is instance-only, switch to a different binding strategy (cannot use x:Static).
4. Ensure MemberType is the actual declaring type of the member, not a derived type where the member is shadowed or inaccessible.
5. If only Member (no MemberType) is set, set MemberType explicitly — member-only resolution is not implemented.

Example fix

// before
var ext = new StaticExtension { Member = "PI", MemberType = typeof(Math) };
// Member="PI" works, but a typo like Member="pi" throws:
var ext2 = new StaticExtension { Member = "pi", MemberType = typeof(Math) };

// after
var ext = new StaticExtension { Member = "PI", MemberType = typeof(Math) };

// Pre-validate the member exists before invoking the extension
public static bool MemberResolves(Type memberType, string member)
{
    if (memberType == null || member == null) return false;
    var flags = BindingFlags.Public | BindingFlags.Static;
    return memberType.GetProperty(member, flags) != null
        || memberType.GetField(member, flags) != null;
}

if (!MemberResolves(ext.MemberType, ext.Member))
    throw new ArgumentException($"No static '{ext.Member}' on {ext.MemberType}");

static bool IsResolvableStaticMember(Type t, string m)
    => t.GetProperty(m, BindingFlags.Public | BindingFlags.Static) != null
    || t.GetField(m, BindingFlags.Public | BindingFlags.Static) != null;

When it happens

Trigger: Setting MemberType and Member where Member names a private/protected static, an instance member, or simply a non-existent member on the type. Also triggered when MemberType is null and Member-only resolution is attempted (the code explicitly notes this case is unsupported).

Common situations: Typos in member names in x:Static directives; referencing instance members when a static was intended; MemberType pointing at a type loaded in a different assembly that lacks InternalsVisibleTo or is internal; relying on case-insensitive matching (the lookup is case-sensitive).

Related errors

• Member property must be set to StaticExtension before callin
• serviceProvider does not implement IXamlNameResolver
• typeName
• type
• Either TypeName or Type must be filled before calling Provid

AI-assisted analysis of unoplatform/uno@0418340488 (2026-08-13). Data as JSON: /api/errors/1eabe65ecc1d3a33. Report an issue: GitHub.