What causes "当前已有 {RegisterFuncCollection.Count} 个注册委托，不能把容量降低到 {value}。" in JeffreySu/WeiXinMPSDK?

Unregister unused accounts/bags first (remove their registrations) until Count <= desired value, then set the new cap.

JeffreySu/WeiXinMPSDK · error · InvalidOperationException

当前已有个注册委托，不能把容量降低到。

Error message

当前已有 {RegisterFuncCollection.Count} 个注册委托，不能把容量降低到 {value}。

What it means

The MaximumRegistrationCallbackCount setter also prevents shrinking the capacity below the number of delegates already registered. If value < RegisterFuncCollection.Count, it throws InvalidOperationException rather than silently dropping existing registrations.

Solutions

Unregister unused accounts/bags first (remove their registrations) until Count <= desired value, then set the new cap.
Set the new value to at least RegisterFuncCollection.Count, or just leave the cap unchanged.
Order initialization: set MaximumRegistrationCallbackCount before any registrations occur.
Query the current count via reflection/registration APIs or simply set a larger value if shrink is unnecessary.

Example fix

// before
MyContainer.MaximumRegistrationCallbackCount = 10; // 50 already registered -> throws
// after
foreach (var stale in staleAppIds) MyContainer.Remove(stale); // unregister first
MyContainer.MaximumRegistrationCallbackCount = Math.Max(10, currentRegisteredCount);

Defensive patterns

Strategy: validation

Validate before calling

var desired = 10;
// currentCount can be tracked by your own registration bookkeeping
if (desired < currentRegisteredCount)
{
    // unregister stale bags first
    foreach (var key in staleKeys) MyContainer.Remove(key);
}
MyContainer.MaximumRegistrationCallbackCount = Math.Max(desired, currentRegisteredCount);

Try / catch

try
{
    MyContainer.MaximumRegistrationCallbackCount = newLimit;
}
catch (InvalidOperationException)
{
    Log("Too many existing registrations to shrink cap; skipping.");
}

Prevention

Set capacity limits before any registrations happen.
Track registered account count in your own registry to validate shrinks.
Unregister accounts during tenant offboarding instead of only shrinking the cap.
Keep the cap generous; shrinking it rarely helps and often fails.

When it happens

Trigger: Lowering MaximumRegistrationCallbackCount on a container that already has more registered callbacks than the new value (e.g. many appIds/tokens registered, then setting the cap lower at runtime).

Common situations: Tightening limits in config after accounts have registered at startup; multi-tenant apps registering hundreds of appIds then a code path reducing the cap; race where registrations happen before the limit configuration runs.

Understand the failure class

Background: "Invalid state transition" errors: "status must be X, actually Y", "already rejected/charging/uninstalled", "cannot ... while running" — what they mean when a library rejects your call — this error's family across 31 libraries.

Related errors

AI-assisted analysis of JeffreySu/WeiXinMPSDK@be573f6f94 (2026-09-12). Data as JSON: /api/errors/25836bc54cc89163. Report an issue: GitHub.

Appendix: source

Thrown at src/Senparc.Weixin/Senparc.Weixin/Containers/BaseContainer.cs:228

            get
            {
                lock (RegistrationCallbackSyncRoot)
                {
                    return _maximumRegistrationCallbackCount;
                }
            }
            set
            {
                if (value <= 0)
                {
                    throw new ArgumentOutOfRangeException(nameof(value), "注册委托容量必须大于 0。");
                }

                lock (RegistrationCallbackSyncRoot)
                {
                    if (value < RegisterFuncCollection.Count)
                    {
                        throw new InvalidOperationException($"当前已有 {RegisterFuncCollection.Count} 个注册委托，不能把容量降低到 {value}。");
                    }

                    _maximumRegistrationCallbackCount = value;
                }
            }
        }

        /// <summary>
        /// 为 SDK 内部注册自动刷新委托，同时执行容量检查。
        /// 保留 <see cref="RegisterFuncCollection"/> 的历史类型，以兼容外部派生容器。
        /// </summary>
        protected static void SetRegistrationCallback(string shortKey, Func<Task<TBag>> registerFunc)
        {
            if (shortKey == null)
            {
                throw new ArgumentNullException(nameof(shortKey));
            }

View on GitHub (pinned to be573f6f94)

当前已有 个注册委托，不能把容量降低到 。