diff --git a/esphome/components/improv_serial/__init__.py b/esphome/components/improv_serial/__init__.py
index 21073a8ab3..67a0f7f4ed 100644
--- a/esphome/components/improv_serial/__init__.py
+++ b/esphome/components/improv_serial/__init__.py
@@ -1,6 +1,8 @@
-from esphome.const import CONF_BAUD_RATE, CONF_ID, CONF_LOGGER
+from esphome.components.logger import USB_CDC, USB_SERIAL_JTAG
+from esphome.const import CONF_BAUD_RATE, CONF_HARDWARE_UART, CONF_ID, CONF_LOGGER
 import esphome.codegen as cg
 import esphome.config_validation as cv
+from esphome.core import CORE
 import esphome.final_validate as fv
 
 CODEOWNERS = ["@esphome/core"]
@@ -17,14 +19,19 @@ CONFIG_SCHEMA = cv.Schema(
 ).extend(cv.COMPONENT_SCHEMA)
 
 
-def validate_logger_baud_rate(config):
+def validate_logger(config):
     logger_conf = fv.full_config.get()[CONF_LOGGER]
     if logger_conf[CONF_BAUD_RATE] == 0:
         raise cv.Invalid("improv_serial requires the logger baud_rate to be not 0")
+    if CORE.using_esp_idf:
+        if logger_conf[CONF_HARDWARE_UART] in [USB_SERIAL_JTAG, USB_CDC]:
+            raise cv.Invalid(
+                "improv_serial does not support the selected logger hardware_uart"
+            )
     return config
 
 
-FINAL_VALIDATE_SCHEMA = validate_logger_baud_rate
+FINAL_VALIDATE_SCHEMA = validate_logger
 
 
 async def to_code(config):
diff --git a/esphome/components/json/json_util.cpp b/esphome/components/json/json_util.cpp
index 2bd8112255..7e701af48b 100644
--- a/esphome/components/json/json_util.cpp
+++ b/esphome/components/json/json_util.cpp
@@ -26,21 +26,33 @@ std::string build_json(const json_build_t &f) {
   const size_t free_heap = heap_caps_get_largest_free_block(MALLOC_CAP_8BIT);
 #endif
 
-  const size_t request_size = std::min(free_heap, (size_t) 512);
-
-  DynamicJsonDocument json_document(request_size);
-  if (json_document.capacity() == 0) {
-    ESP_LOGE(TAG, "Could not allocate memory for JSON document! Requested %u bytes, largest free heap block: %u bytes",
-             request_size, free_heap);
-    return "{}";
+  size_t request_size = std::min(free_heap, (size_t) 512);
+  while (true) {
+    ESP_LOGV(TAG, "Attempting to allocate %u bytes for JSON serialization", request_size);
+    DynamicJsonDocument json_document(request_size);
+    if (json_document.capacity() == 0) {
+      ESP_LOGE(TAG,
+               "Could not allocate memory for JSON document! Requested %u bytes, largest free heap block: %u bytes",
+               request_size, free_heap);
+      return "{}";
+    }
+    JsonObject root = json_document.to<JsonObject>();
+    f(root);
+    if (json_document.overflowed()) {
+      if (request_size == free_heap) {
+        ESP_LOGE(TAG, "Could not allocate memory for JSON document! Overflowed largest free heap block: %u bytes",
+                 free_heap);
+        return "{}";
+      }
+      request_size = std::min(request_size * 2, free_heap);
+      continue;
+    }
+    json_document.shrinkToFit();
+    ESP_LOGV(TAG, "Size after shrink %u bytes", json_document.capacity());
+    std::string output;
+    serializeJson(json_document, output);
+    return output;
   }
-  JsonObject root = json_document.to<JsonObject>();
-  f(root);
-  json_document.shrinkToFit();
-  ESP_LOGV(TAG, "Size after shrink %u bytes", json_document.capacity());
-  std::string output;
-  serializeJson(json_document, output);
-  return output;
 }
 
 void parse_json(const std::string &data, const json_parse_t &f) {
diff --git a/esphome/const.py b/esphome/const.py
index 7717f709ec..03d8c98712 100644
--- a/esphome/const.py
+++ b/esphome/const.py
@@ -1,6 +1,6 @@
 """Constants used by esphome."""
 
-__version__ = "2022.5.0b2"
+__version__ = "2022.5.0b3"
 
 ALLOWED_NAME_CHARS = "abcdefghijklmnopqrstuvwxyz0123456789-_"