diff --git a/runtime/rpc.cpp b/runtime/rpc.cpp
index 9a083c71e1..be61583e21 100644
--- a/runtime/rpc.cpp
+++ b/runtime/rpc.cpp
@@ -24,9 +24,12 @@
 #include "runtime/tl/rpc_server.h"
 #include "runtime/tl/rpc_tl_query.h"
 #include "runtime/tl/tl_builtins.h"
+#include "runtime/tl/tl_magics_decoding.h"
 #include "runtime/zlib.h"
 #include "server/php-queries.h"
 
+DEFINE_VERBOSITY(rpc);
+
 static const int GZIP_PACKED = 0x3072cfa1;
 
 const string tl_str_("");
@@ -816,8 +819,12 @@ void process_rpc_error(int32_t request_id, int32_t error_code, const char *error
     php_assert (request->resumable_id != -1);
     return;
   }
-  if (!is_fake_error && kphp_tracing::is_turned_on()) {
-    kphp_tracing::on_rpc_query_fail(request_id, error_code);
+  if (!is_fake_error) {
+    tvkprintf(rpc, 1, "RPC error: error_code=%d, request_id=%d, tl_function=%s(0x%08x), actor_id=%d\n",
+             error_code, request_id, tl_magic_convert_to_name(request->function_magic), request->function_magic, request->actor_or_port);
+    if (kphp_tracing::is_turned_on()) {
+      kphp_tracing::on_rpc_query_fail(request_id, error_code);
+    }
   }
   int64_t resumable_id = request->resumable_id;
   request->resumable_id = -2;
diff --git a/runtime/rpc.h b/runtime/rpc.h
index 3884f25bf6..51cfc4b6b8 100644
--- a/runtime/rpc.h
+++ b/runtime/rpc.h
@@ -7,12 +7,15 @@
 #include <memory>
 
 #include "common/algorithms/hashes.h"
+#include "common/kprintf.h"
 #include "runtime/dummy-visitor-methods.h"
 #include "runtime/kphp_core.h"
 #include "runtime/net_events.h"
 #include "runtime/resumable.h"
 #include "runtime/to-array-processor.h"
 
+DECLARE_VERBOSITY(rpc);
+
 struct rpc_request {
   int64_t resumable_id; // == 0 - default, > 0 if not finished, -1 if received an answer, -2 if received an error, -3 if answer was gotten
   union {
diff --git a/server/confdata-binlog-replay.cpp b/server/confdata-binlog-replay.cpp
index 4955bdf73e..cac6fb3376 100644
--- a/server/confdata-binlog-replay.cpp
+++ b/server/confdata-binlog-replay.cpp
@@ -11,6 +11,7 @@
 #include <map>
 
 #include "common/binlog/binlog-replayer.h"
+#include "common/dl-utils-lite.h"
 #include "common/precise-time.h"
 #include "common/server/engine-settings.h"
 #include "common/server/init-binlog.h"
@@ -189,7 +190,9 @@ class ConfdataBinlogReplayer : vk::binlog::replayer {
         *updating_confdata_storage_ = previous_confdata_storage;
       } else {
         // strictly speaking, they should be identical, but it's too hard to verify
-        assert(updating_confdata_storage_->size() == previous_confdata_storage.size());
+        dl_assert(updating_confdata_storage_->size() == previous_confdata_storage.size(),
+                  dl_pstr("Can't update confdata from binlog: 'updating_confdata' and 'previous_confdata' must be identical, "
+                          "but they have different sizes (%zu != %zu)\n", updating_confdata_storage_->size(), previous_confdata_storage.size()));
       }
     }
   }