diff --git a/include/errmsg.h b/include/errmsg.h
index 0e6d24e0..26743ff1 100644
--- a/include/errmsg.h
+++ b/include/errmsg.h
@@ -116,10 +116,11 @@ extern const char *mariadb_client_errors[];	/* Error messages */
 #define CR_BINLOG_SEMI_SYNC_ERROR 5023
 #define CR_INVALID_CLIENT_FLAG 5024
 #define CR_STMT_NO_RESULT 5025
+#define CR_ERR_MISSING_ERROR_INFO 5026
 
 /* Always last, if you add new error codes please update the
    value for CR_MARIADB_LAST_ERROR */
-#define CR_MARIADB_LAST_ERROR CR_STMT_NO_RESULT
+#define CR_MARIADB_LAST_ERROR CR_ERR_MISSING_ERROR_INFO
 
 #endif
 
@@ -128,6 +129,6 @@ extern const char *mariadb_client_errors[];	/* Error messages */
 
 #define ER(code) IS_MYSQL_ERROR((code)) ? client_errors[(code) - CR_MIN_ERROR] : \
                  IS_MARIADB_ERROR((code)) ?  mariadb_client_errors[(code) - CER_MIN_ERROR] : \
-                 "Unknown or undefined error code" 
+                 "Unknown or undefined error code"
 #define CER(code) ER((code))
 
diff --git a/include/ma_context.h b/include/ma_context.h
index 4c3f0d8d..966fd0cd 100644
--- a/include/ma_context.h
+++ b/include/ma_context.h
@@ -26,8 +26,33 @@
   (This particular implementation uses Posix ucontext swapcontext().)
 */
 
+
+/*
+  When running with address sanitizer, the stack switching can cause confusion
+  unless the __sanitizer_{start,finish}_switch_fiber() functions are used
+  (CONC-618).
+
+  In this case prefer the use of boost::context or ucontext, which should have
+  this instrumentation, over our custom assembler variants.
+*/
+#ifdef __has_feature
+   /* Clang */
+#  if __has_feature(address_sanitizer)
+#    define ASAN_PREFER_NON_ASM 1
+#  endif
+#else
+   /* GCC */
+#  ifdef __SANITIZE_ADDRESS__
+#    define ASAN_PREFER_NON_ASM 1
+#  endif
+#endif
+
 #ifdef _WIN32
 #define MY_CONTEXT_USE_WIN32_FIBERS 1
+#elif defined(ASAN_PREFER_NON_ASM) && defined(HAVE_BOOST_CONTEXT_H)
+#define MY_CONTEXT_USE_BOOST_CONTEXT
+#elif defined(ASAN_PREFER_NON_ASM) && defined(HAVE_UCONTEXT_H)
+#define MY_CONTEXT_USE_UCONTEXT
 #elif defined(__GNUC__) && __GNUC__ >= 3 && defined(__x86_64__) && !defined(__ILP32__)
 #define MY_CONTEXT_USE_X86_64_GCC_ASM
 #elif defined(__GNUC__) && __GNUC__ >= 3 && defined(__i386__)
diff --git a/libmariadb/CMakeLists.txt b/libmariadb/CMakeLists.txt
index 1985b44f..69e8683c 100644
--- a/libmariadb/CMakeLists.txt
+++ b/libmariadb/CMakeLists.txt
@@ -168,12 +168,6 @@ SET(MYSQL_LIB_SYMBOLS
  mysql_use_result
  mysql_warning_count)
 
-# some gcc versions fail to compile asm parts of my_context.c,
-# if build type is "Release" (see CONC-133), so we need to add -g flag
-IF(CMAKE_COMPILER_IS_GNUCC AND CMAKE_BUILD_TYPE MATCHES "Release")
-  SET_SOURCE_FILES_PROPERTIES(my_context.c PROPERTIES COMPILE_FLAGS -g)
-ENDIF()
-
 IF(ZLIB_FOUND AND WITH_EXTERNAL_ZLIB)
   INCLUDE_DIRECTORIES(${ZLIB_INCLUDE_DIR})
 ELSE()
diff --git a/libmariadb/ma_context.c b/libmariadb/ma_context.c
index f9431d04..224783b2 100644
--- a/libmariadb/ma_context.c
+++ b/libmariadb/ma_context.c
@@ -105,6 +105,7 @@ my_context_spawn(struct my_context *c, void (*f)(void *), void *d)
   c->user_func= f;
   c->user_data= d;
   c->active= 1;
+  u.a[1]= 0;   /* Otherwise can give uninitialized warnings on 32-bit. */
   u.p= c;
   makecontext(&c->spawned_context, (uc_func_t)my_context_spawn_internal, 2,
               u.a[0], u.a[1]);
@@ -204,7 +205,7 @@ my_context_spawn(struct my_context *c, void (*f)(void *), void *d)
     (
      "movq %%rsp, (%[save])\n\t"
      "movq %[stack], %%rsp\n\t"
-#if (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 4) || __clang__) && !defined(__INTEL_COMPILER)
+#if defined(__GCC_HAVE_DWARF2_CFI_ASM) || (defined(__clang__) && __clang_major__ < 13)
      /*
        This emits a DWARF DW_CFA_undefined directive to make the return address
        undefined. This indicates that this is the top of the stack frame, and
@@ -440,7 +441,7 @@ my_context_spawn(struct my_context *c, void (*f)(void *), void *d)
     (
      "movl %%esp, (%[save])\n\t"
      "movl %[stack], %%esp\n\t"
-#if (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 4) || __clang__) && !defined(__INTEL_COMPILER)
+#if defined(__GCC_HAVE_DWARF2_CFI_ASM) || (defined(__clang__) && __clang_major__ < 13)
      /*
        This emits a DWARF DW_CFA_undefined directive to make the return address
        undefined. This indicates that this is the top of the stack frame, and
@@ -675,7 +676,7 @@ my_context_spawn(struct my_context *c, void (*f)(void *), void *d)
     (
      "mov x10, sp\n\t"
      "mov sp, %[stack]\n\t"
-#if !defined(__INTEL_COMPILER)
+#if defined(__GCC_HAVE_DWARF2_CFI_ASM) || (defined(__clang__) && __clang_major__ < 13)
      /*
        This emits a DWARF DW_CFA_undefined directive to make the return address
        (UNW_AARCH64_X30) undefined. This indicates that this is the top of the
diff --git a/libmariadb/ma_errmsg.c b/libmariadb/ma_errmsg.c
index 53890f87..a5b528c1 100644
--- a/libmariadb/ma_errmsg.c
+++ b/libmariadb/ma_errmsg.c
@@ -120,6 +120,7 @@ const char *mariadb_client_errors[] =
   /* 5023 */ "Semi sync request error: %s",
   /* 5024 */ "Invalid client flags (%lu) specified. Supported flags: %lu",
   /* 5025 */ "Statement has no result set",
+  /* 5026 */ "Server returned an error packet without further information",
   ""
 };
 
diff --git a/libmariadb/mariadb_lib.c b/libmariadb/mariadb_lib.c
index aaaf5576..dcd409a7 100644
--- a/libmariadb/mariadb_lib.c
+++ b/libmariadb/mariadb_lib.c
@@ -80,7 +80,7 @@
 #define strncasecmp _strnicmp
 #endif
 
-#define ASYNC_CONTEXT_DEFAULT_STACK_SIZE (4096*15)
+#define ASYNC_CONTEXT_DEFAULT_STACK_SIZE (256*1024)
 #define MA_RPL_VERSION_HACK "5.5.5-"
 
 #define CHARSET_NAME_LEN 64
@@ -273,6 +273,11 @@ restart:
         ma_strmake(net->last_error,(char*) pos,
                 min(len,sizeof(net->last_error)-1));
       }
+      /* MDEV-35935: if server sends error packet without error, we have to
+         set error manually */
+      if (!net->last_errno) {
+        my_set_error(mysql, CR_ERR_MISSING_ERROR_INFO, SQLSTATE_UNKNOWN, 0);
+      }
     }
     else
     {
diff --git a/unittest/libmariadb/errors.c b/unittest/libmariadb/errors.c
index b0914782..2f895c9d 100644
--- a/unittest/libmariadb/errors.c
+++ b/unittest/libmariadb/errors.c
@@ -272,8 +272,77 @@ static int test_parse_error_and_bad_length(MYSQL *mysql)
   return OK;
 }
 
+#define TEST_ARRAY_SIZE 1024
+
+static int test_mdev35935(MYSQL *mysql)
+{
+  MYSQL_STMT *stmt= mysql_stmt_init(mysql);
+  const char *stmt_str= "INSERT INTO bulk1 (a,b) VALUES (?,?)";
+  unsigned int array_size= TEST_ARRAY_SIZE;
+  int rc;
+  unsigned int i;
+  char **buffer;
+  unsigned long *lengths;
+  unsigned int *vals;
+  MYSQL_BIND bind[2];
+  const char *data= "test";
+
+  SKIP_MYSQL(mysql);
+
+  rc= mysql_select_db(mysql, schema);
+
+  rc= mysql_query(mysql, "DROP TABLE IF EXISTS bulk1");
+  check_mysql_rc(rc, mysql);
+
+  rc= mysql_query(mysql, "CREATE TABLE bulk1 (a int , b VARCHAR(255))");
+  check_mysql_rc(rc, mysql);
+
+  rc= mysql_stmt_prepare(stmt, SL(stmt_str));
+  check_stmt_rc(rc, stmt);
+
+  rc= mysql_query(mysql, "ALTER TABLE bulk1 ADD c int");
+  check_mysql_rc(rc, mysql);
+
+  /* allocate memory */
+  buffer= calloc(TEST_ARRAY_SIZE, sizeof(char *));
+  lengths= calloc(TEST_ARRAY_SIZE, sizeof *lengths);
+  vals= calloc(TEST_ARRAY_SIZE, sizeof *vals);
+
+  for (i=0; i < TEST_ARRAY_SIZE; i++)
+  {
+    buffer[i]= (void *)data;
+    lengths[i]= -1;
+    vals[i]= i;
+  }
+
+  memset(bind, 0, sizeof(MYSQL_BIND) * 2);
+  bind[0].buffer_type= MYSQL_TYPE_LONG;
+  bind[0].buffer= vals;
+  bind[1].buffer_type= MYSQL_TYPE_STRING;
+  bind[1].buffer= (void *)buffer;
+  bind[1].length= (unsigned long *)lengths;
+
+  rc= mysql_stmt_attr_set(stmt, STMT_ATTR_ARRAY_SIZE, &array_size);
+  check_stmt_rc(rc, stmt);
+
+  rc= mysql_stmt_bind_param(stmt, bind);
+  check_stmt_rc(rc, stmt);
+
+  if ((rc= mysql_stmt_execute(stmt)))
+  {
+    FAIL_IF((!mysql_stmt_errno(stmt) || !mysql_errno(mysql)), "Error number > 0 expected");
+  }
+
+  mysql_stmt_close(stmt);
+  rc= mysql_query(mysql, "DROP TABLE IF EXISTS bulk1");
+  check_mysql_rc(rc, mysql);
+  return OK;
+}
+
+
 
 struct my_tests_st my_tests[] = {
+  {"test_mdev35935", test_mdev35935, TEST_CONNECTION_DEFAULT, 0, NULL , NULL},
   {"test_client_warnings", test_client_warnings, TEST_CONNECTION_DEFAULT, 0, NULL , NULL},
   {"test_ps_client_warnings", test_ps_client_warnings, TEST_CONNECTION_DEFAULT, 0, NULL , NULL},
   {"test_server_warnings", test_server_warnings, TEST_CONNECTION_DEFAULT, 0, NULL , NULL},
diff --git a/unittest/libmariadb/ps_bugs.c b/unittest/libmariadb/ps_bugs.c
index 374f2300..09d53e57 100644
--- a/unittest/libmariadb/ps_bugs.c
+++ b/unittest/libmariadb/ps_bugs.c
@@ -5027,11 +5027,14 @@ static int test_conc_fraction(MYSQL *mysql)
 
     diag("second_part: %ld", tm.second_part);
 
-    expected= i > 6 ? 123456 : frac * (unsigned int)powl(10, (6 - i));
+    expected= frac * 100000;
+    while (expected >= 1000000)
+      expected /= 10;
 
     if (tm.second_part != expected)
     {
       diag("Error: tm.second_part=%ld expected=%ld", tm.second_part, expected);
+      mysql_stmt_close(stmt);
       return FAIL;
     }
   }
@@ -5618,6 +5621,7 @@ static int test_conc623(MYSQL *mysql)
   rc= mysql_stmt_attr_set(stmt, STMT_ATTR_CB_PARAM, conc623_param_callback);
   check_stmt_rc(rc, stmt);
 
+  memset(&bind, 0, sizeof(MYSQL_BIND));
   bind.buffer_type= MYSQL_TYPE_LONG;
   rc= mysql_stmt_bind_param(stmt, &bind);
   check_stmt_rc(rc, stmt);