diff --git a/src/nvim/msgpack_rpc/channel.c b/src/nvim/msgpack_rpc/channel.c
index 5564bfa1be..aa6008558f 100644
--- a/src/nvim/msgpack_rpc/channel.c
+++ b/src/nvim/msgpack_rpc/channel.c
@@ -436,6 +436,11 @@ static void handle_request(Channel *channel, msgpack_object *request)
                                      &error,
                                      NIL,
                                      &out_buffer));
+    char buf[256];
+    snprintf(buf, sizeof(buf),
+             "Channel %" PRIu64 " sent an invalid message, closing.",
+             channel->id);
+    call_set_error(channel, buf);
     return;
   }
 
@@ -491,6 +496,10 @@ static bool channel_write(Channel *channel, WBuffer *buffer)
 {
   bool success;
 
+  if (channel->closed) {
+    return false;
+  }
+
   if (channel->is_job) {
     success = job_write(channel->data.job, buffer);
   } else {
diff --git a/src/nvim/msgpack_rpc/helpers.c b/src/nvim/msgpack_rpc/helpers.c
index 4414aadb15..a702d4f256 100644
--- a/src/nvim/msgpack_rpc/helpers.c
+++ b/src/nvim/msgpack_rpc/helpers.c
@@ -377,14 +377,17 @@ void msgpack_rpc_validate(uint64_t *response_id,
   // Validate the basic structure of the msgpack-rpc payload
   if (req->type != MSGPACK_OBJECT_ARRAY) {
     api_set_error(err, Validation, _("Request is not an array"));
+    return;
   }
 
   if (req->via.array.size != 4) {
     api_set_error(err, Validation, _("Request array size should be 4"));
+    return;
   }
 
   if (req->via.array.ptr[1].type != MSGPACK_OBJECT_POSITIVE_INTEGER) {
     api_set_error(err, Validation, _("Id must be a positive integer"));
+    return;
   }
 
   // Set the response id, which is the same as the request
@@ -392,18 +395,22 @@ void msgpack_rpc_validate(uint64_t *response_id,
 
   if (req->via.array.ptr[0].type != MSGPACK_OBJECT_POSITIVE_INTEGER) {
     api_set_error(err, Validation, _("Message type must be an integer"));
+    return;
   }
 
   if (req->via.array.ptr[0].via.u64 != 0) {
     api_set_error(err, Validation, _("Message type must be 0"));
+    return;
   }
 
   if (req->via.array.ptr[2].type != MSGPACK_OBJECT_BIN
     && req->via.array.ptr[2].type != MSGPACK_OBJECT_STR) {
     api_set_error(err, Validation, _("Method must be a string"));
+    return;
   }
 
   if (req->via.array.ptr[3].type != MSGPACK_OBJECT_ARRAY) {
-    api_set_error(err, Validation, _("Paremeters must be an array"));
+    api_set_error(err, Validation, _("Parameters must be an array"));
+    return;
   }
 }