What causes "invalid capacity: {capacity}" in egametang/ET?

Clamp the computed capacity to >= 0 before calling SetCapacity (e.g. Math.Max(0, computed)).

invalid capacity: {capacity}

Error message

invalid capacity: {capacity}

What it means

Thrown by the SERVER-side ItemComponentSystem.SetCapacity when capacity < 0. SetCapacity writes self.Capacity and then grows the SlotItems container via EnsureSlotContainerSize. A negative capacity is meaningless for a slot list, so the guard rejects it hard. Note the CLIENT-side SetCapacity (Client/ItemComponentSystem.cs:76) does NOT throw — it logs and returns — so this throw is server-authoritative only.

Source

Thrown at Packages/cn.etetet.item/Scripts/Hotfix/Server/ItemComponentSystem.cs:150

                {
                    item.Dispose();
                }
                self.SlotItems[i] = default;
            }
        }

        #endregion

        #region 业务辅助方法

        /// <summary>
        /// 设置背包容量
        /// </summary>
        public static void SetCapacity(this ItemComponent self, int capacity)
        {
            if (capacity < 0)
            {
                throw new Exception($"invalid capacity: {capacity}");
            }

            self.Capacity = capacity;
            EnsureSlotContainerSize(self, capacity);
        }

        /// <summary>
        /// 清空指定槽位
        /// </summary>
        public static void ClearSlot(this ItemComponent self, int slotIndex)
        {
            if ((uint)slotIndex >= (uint)self.SlotItems.Count)
            {
                return;
            }

            self.SlotItems[slotIndex] = default;
        }

View on GitHub (pinned to 5cab01f7a8)

Solutions

Clamp the computed capacity to >= 0 before calling SetCapacity (e.g. Math.Max(0, computed)).
Fix the config sentinel: make 'not found' return 0 or a real default, never -1.
Add a precondition at the caller (ItemHelper.SetCapacity) so the raw server API never sees a negative value.

Example fix

// before
int cap = configTable.Get(player.Level); // returns -1 when missing
component.SetCapacity(cap);

// after
int cap = configTable.Get(player.Level);
if (cap < 0) cap = 0; // explicit default
component.SetCapacity(cap);

Defensive patterns

Strategy: validation

Validate before calling

int safeCap = capacity < 0 ? 0 : capacity;
component.SetCapacity(safeCap);

Prevention

Never use -1 as a 'not found' sentinel for capacity; use 0 or a nullable.
Clamp config-driven capacity to >= 0 at the data source.
Unit-test SetCapacity with boundary values (0, negative, large).

When it happens

Trigger: Calling the server extension ItemComponentSystem.SetCapacity(this ItemComponent, int) (line 146) with a negative int. Reached from ItemHelper.SetCapacity (line 14) which forwards directly, or from any server code that computes capacity from player level/config and underflows.

Common situations: A config-driven capacity table returns -1 as a 'not found' sentinel and is passed straight in; an arithmetic underflow (e.g. baseCapacity - penalty where penalty > baseCapacity); a deserialized capacity field corrupted to a negative value.

Related errors

AI-assisted analysis of egametang/ET@5cab01f7a8 (2026-08-13). Data as JSON: /api/errors/6177d264e0287c5c. Report an issue: GitHub.