Update

Author: JamesNK

src/Grpc.AspNetCore.Server/GrpcServiceOptions.cs

@@ -29,6 +29,8 @@ public class GrpcServiceOptions
     internal IList<ICompressionProvider>? _compressionProviders;
     internal int? _maxReceiveMessageSize;
     internal int? _maxSendMessageSize;
+    internal bool _maxSendMessageSizeSpecified;
+    internal bool _maxReceiveMessageSizeSpecified;
 
     /// <summary>
     /// Gets or sets the maximum message size in bytes that can be sent from the server.
@@ -51,7 +53,18 @@ public int? MaxSendMessageSize
     /// Gets or sets a flag indicating whether <see cref="MaxSendMessageSize"/> is specified.
     /// This flag is automatically set to true when <see cref="MaxSendMessageSize"/> is configured.
     /// </summary>
-    public bool MaxSendMessageSizeSpecified { get; set; }
+    public bool MaxSendMessageSizeSpecified
+    {
+        get => _maxSendMessageSizeSpecified;
+        set
+        {
+            _maxSendMessageSizeSpecified = value;
+            if (!_maxSendMessageSizeSpecified)
+            {
+                _maxSendMessageSize = null;
+            }
+        }
+    }
 
     /// <summary>
     /// Gets or sets the maximum message size in bytes that can be received by the server.
@@ -74,7 +87,18 @@ public int? MaxReceiveMessageSize
     /// Gets or sets a flag indicating whether <see cref="MaxReceiveMessageSize"/> is specified.
     /// This flag is automatically set to true when <see cref="MaxReceiveMessageSize"/> is configured.
     /// </summary>
-    public bool MaxReceiveMessageSizeSpecified { get; set; }
+    public bool MaxReceiveMessageSizeSpecified
+    {
+        get => _maxReceiveMessageSizeSpecified;
+        set
+        {
+            _maxReceiveMessageSizeSpecified = value;
+            if (!_maxReceiveMessageSizeSpecified)
+            {
+                _maxReceiveMessageSize = null;
+            }
+        }
+    }
 
     /// <summary>
     /// Gets or sets a value indicating whether detailed error messages are sent to the peer.

src/Grpc.AspNetCore.Server/Internal/GrpcServiceOptionsSetup.cs

@@ -52,8 +52,12 @@ public GrpcServiceOptionsSetup(IOptions<GrpcServiceOptions> options)
 
     public void Configure(GrpcServiceOptions<TService> options)
     {
-        options.MaxReceiveMessageSize = _options.MaxReceiveMessageSize;
-        options.MaxSendMessageSize = _options.MaxSendMessageSize;
+        // Copy internal fields to avoid running logic in property setters.
+        options._maxReceiveMessageSize = _options._maxReceiveMessageSize;
+        options._maxReceiveMessageSizeSpecified = _options._maxReceiveMessageSizeSpecified;
+        options._maxSendMessageSize = _options._maxSendMessageSize;
+        options._maxSendMessageSizeSpecified = _options._maxSendMessageSizeSpecified;
+
         options.EnableDetailedErrors = _options.EnableDetailedErrors;
         options.ResponseCompressionAlgorithm = _options.ResponseCompressionAlgorithm;
         options.ResponseCompressionLevel = _options.ResponseCompressionLevel;