pardeike/Harmony · error · ArgumentException

No field found for and

Error message

No field found for {type} and {name}

What it means

CodeInstruction.LoadField resolves the field with AccessTools.Field and emits an LDFLD/LDSFLD (or address variant). If the field does not exist on the type, Harmony throws ArgumentException instead of emitting an invalid field load.

Solutions

1. Correct the field name (exact, case-sensitive) and confirm it exists with AccessTools.Field(type, name)
2. If targeting a property, use CodeInstruction.LoadArgument/Call on its getter or the backing-field name instead
3. AccessTools.Field on the declaring type where the field is actually defined
4. Validate at patch init and fall back to a safe path or log if the field vanished in a new target version

Example fix

// before
new CodeInstruction(OpCodes.Ldarg_0), CodeInstruction.LoadField(typeof(Player), "healt")
// after
new CodeInstruction(OpCodes.Ldarg_0), CodeInstruction.LoadField(typeof(Player), nameof(Player.health))

if (AccessTools.Field(type, name) is null) throw new InvalidOperationException($"Field {type}.{name} not found");

bool FieldExists(Type t, string n) => AccessTools.Field(t, n) is not null;

try { il.Append(CodeInstruction.LoadField(type, name)); } catch (ArgumentException ex) { log.Error($"LoadField failed for {type}.{name}", ex); throw; }

When it happens

Trigger: CodeInstruction.LoadField(typeof(T), "fieldName") where the field was renamed, removed, is defined on a base/derived type not resolved, or the name's casing differs.

Common situations: Target mod/library version changed private field names; typo in the field name; trying to auto-load a property or auto-property backing field using the property name instead of '<Name>k__BackingField'.

Understand the failure class

Background: 'Could not be found', 'does not exist', 'not found in database': the resource-not-found family when an ID, slug, key, or URI lookup comes back empty — this error's family across 20 libraries.

Related errors

• No method found for type=
• No method found for , parameters= , generics=
• Ambiguous match for HarmonyMethod
• VariableState: variable of type
• VariableState: variable named

AI-assisted analysis of pardeike/Harmony@e7872dc170 (2026-09-15). Data as JSON: /api/errors/553d8d14e0013622. Report an issue: GitHub.

Appendix: source

Thrown at Harmony/Public/CodeInstruction.cs:210

				il.Emit(OpCodes.Ldarg, i);

			il.Emit(OpCodes.Callvirt, AccessTools.Method(typeof(T), nameof(Action.Invoke)));
			il.Emit(OpCodes.Ret);

			return new CodeInstruction(OpCodes.Call, closureMethod.Generate());
		}

		// --- FIELDS

		/// <summary>Creates a CodeInstruction loading a field (LD[S]FLD[A])</summary>
		/// <param name="type">The class/type where the field is defined</param>
		/// <param name="name">The name of the field (case sensitive)</param>
		/// <param name="useAddress">Use address of field</param>
		/// <returns>A new Codeinstruction</returns>
		public static CodeInstruction LoadField(Type type, string name, bool useAddress = false)
		{
			var field = AccessTools.Field(type, name);
			if (field is null) throw new ArgumentException($"No field found for {type} and {name}");
			return new CodeInstruction(useAddress ? (field.IsStatic ? OpCodes.Ldsflda : OpCodes.Ldflda) : (field.IsStatic ? OpCodes.Ldsfld : OpCodes.Ldfld), field);
		}

		/// <summary>Creates a CodeInstruction storing to a field (ST[S]FLD)</summary>
		/// <param name="type">The class/type where the field is defined</param>
		/// <param name="name">The name of the field (case sensitive)</param>
		/// <returns>A new Codeinstruction</returns>
		public static CodeInstruction StoreField(Type type, string name)
		{
			var field = AccessTools.Field(type, name);
			if (field is null) throw new ArgumentException($"No field found for {type} and {name}");
			return new CodeInstruction(field.IsStatic ? OpCodes.Stsfld : OpCodes.Stfld, field);
		}

		// --- LOCALS

		/// <summary>Creates a CodeInstruction loading a local with the given index, using the shorter forms when possible</summary>
		/// <param name="index">The index where the local is stored</param>

View on GitHub (pinned to e7872dc170)