diff --git a/esphome/__main__.py b/esphome/__main__.py
index 1db046edf0..327741bb75 100644
--- a/esphome/__main__.py
+++ b/esphome/__main__.py
@@ -779,7 +779,7 @@ def command_update_all(args: ArgsProtocol) -> int | None:
         safe_print(f"{half_line}{middle_text}{half_line}")
 
     for f in files:
-        safe_print(f"Updating {color(AnsiFore.CYAN, f)}")
+        safe_print(f"Updating {color(AnsiFore.CYAN, str(f))}")
         safe_print("-" * twidth)
         safe_print()
         if CORE.dashboard:
@@ -791,10 +791,10 @@ def command_update_all(args: ArgsProtocol) -> int | None:
                 "esphome", "run", f, "--no-logs", "--device", "OTA"
             )
         if rc == 0:
-            print_bar(f"[{color(AnsiFore.BOLD_GREEN, 'SUCCESS')}] {f}")
+            print_bar(f"[{color(AnsiFore.BOLD_GREEN, 'SUCCESS')}] {str(f)}")
             success[f] = True
         else:
-            print_bar(f"[{color(AnsiFore.BOLD_RED, 'ERROR')}] {f}")
+            print_bar(f"[{color(AnsiFore.BOLD_RED, 'ERROR')}] {str(f)}")
             success[f] = False
 
         safe_print()
@@ -805,9 +805,9 @@ def command_update_all(args: ArgsProtocol) -> int | None:
     failed = 0
     for f in files:
         if success[f]:
-            safe_print(f"  - {f}: {color(AnsiFore.GREEN, 'SUCCESS')}")
+            safe_print(f"  - {str(f)}: {color(AnsiFore.GREEN, 'SUCCESS')}")
         else:
-            safe_print(f"  - {f}: {color(AnsiFore.BOLD_RED, 'FAILED')}")
+            safe_print(f"  - {str(f)}: {color(AnsiFore.BOLD_RED, 'FAILED')}")
             failed += 1
     return failed
 
diff --git a/esphome/components/number/__init__.py b/esphome/components/number/__init__.py
index c2cad2f7f1..76a7b05ea1 100644
--- a/esphome/components/number/__init__.py
+++ b/esphome/components/number/__init__.py
@@ -51,6 +51,7 @@ from esphome.const import (
     DEVICE_CLASS_OZONE,
     DEVICE_CLASS_PH,
     DEVICE_CLASS_PM1,
+    DEVICE_CLASS_PM4,
     DEVICE_CLASS_PM10,
     DEVICE_CLASS_PM25,
     DEVICE_CLASS_POWER,
@@ -116,6 +117,7 @@ DEVICE_CLASSES = [
     DEVICE_CLASS_PM1,
     DEVICE_CLASS_PM10,
     DEVICE_CLASS_PM25,
+    DEVICE_CLASS_PM4,
     DEVICE_CLASS_POWER,
     DEVICE_CLASS_POWER_FACTOR,
     DEVICE_CLASS_PRECIPITATION,
diff --git a/esphome/components/sensirion_common/i2c_sensirion.cpp b/esphome/components/sensirion_common/i2c_sensirion.cpp
index 22c4b0e53c..9eac6b4525 100644
--- a/esphome/components/sensirion_common/i2c_sensirion.cpp
+++ b/esphome/components/sensirion_common/i2c_sensirion.cpp
@@ -76,7 +76,8 @@ bool SensirionI2CDevice::write_command_(uint16_t command, CommandLen command_len
     temp[raw_idx++] = data[i] >> 8;
 #endif
     // Use MSB first since Sensirion devices use CRC-8 with MSB first
-    temp[raw_idx++] = crc8(&temp[raw_idx - 2], 2, 0xFF, CRC_POLYNOMIAL, true);
+    uint8_t crc = crc8(&temp[raw_idx - 2], 2, 0xFF, CRC_POLYNOMIAL, true);
+    temp[raw_idx++] = crc;
   }
   this->last_error_ = this->write(temp, raw_idx);
   return this->last_error_ == i2c::ERROR_OK;
diff --git a/esphome/components/sensor/__init__.py b/esphome/components/sensor/__init__.py
index fe9822b3ca..2b99f68ac0 100644
--- a/esphome/components/sensor/__init__.py
+++ b/esphome/components/sensor/__init__.py
@@ -74,6 +74,7 @@ from esphome.const import (
     DEVICE_CLASS_OZONE,
     DEVICE_CLASS_PH,
     DEVICE_CLASS_PM1,
+    DEVICE_CLASS_PM4,
     DEVICE_CLASS_PM10,
     DEVICE_CLASS_PM25,
     DEVICE_CLASS_POWER,
@@ -143,6 +144,7 @@ DEVICE_CLASSES = [
     DEVICE_CLASS_PM1,
     DEVICE_CLASS_PM10,
     DEVICE_CLASS_PM25,
+    DEVICE_CLASS_PM4,
     DEVICE_CLASS_POWER,
     DEVICE_CLASS_POWER_FACTOR,
     DEVICE_CLASS_PRECIPITATION,
diff --git a/esphome/const.py b/esphome/const.py
index c91c81f484..3e93200f14 100644
--- a/esphome/const.py
+++ b/esphome/const.py
@@ -1269,6 +1269,7 @@ DEVICE_CLASS_PLUG = "plug"
 DEVICE_CLASS_PM1 = "pm1"
 DEVICE_CLASS_PM10 = "pm10"
 DEVICE_CLASS_PM25 = "pm25"
+DEVICE_CLASS_PM4 = "pm4"
 DEVICE_CLASS_POWER = "power"
 DEVICE_CLASS_POWER_FACTOR = "power_factor"
 DEVICE_CLASS_PRECIPITATION = "precipitation"
diff --git a/tests/unit_tests/test_main.py b/tests/unit_tests/test_main.py
index e805ecb2eb..da280b1fd8 100644
--- a/tests/unit_tests/test_main.py
+++ b/tests/unit_tests/test_main.py
@@ -5,6 +5,7 @@ from __future__ import annotations
 from collections.abc import Generator
 from dataclasses import dataclass
 from pathlib import Path
+import re
 from typing import Any
 from unittest.mock import MagicMock, Mock, patch
 
@@ -15,6 +16,7 @@ from esphome.__main__ import (
     Purpose,
     choose_upload_log_host,
     command_rename,
+    command_update_all,
     command_wizard,
     get_port_type,
     has_ip_address,
@@ -55,6 +57,17 @@ from esphome.const import (
 from esphome.core import CORE, EsphomeError
 
 
+def strip_ansi_codes(text: str) -> str:
+    """Remove ANSI escape codes from text.
+
+    This helps make test assertions cleaner by removing color codes and other
+    terminal formatting that can make tests brittle.
+    """
+    # Pattern to match ANSI escape sequences
+    ansi_escape = re.compile(r"\x1B(?:[@-Z\\-_]|\[[0-?]*[ -/]*[@-~])")
+    return ansi_escape.sub("", text)
+
+
 @dataclass
 class MockSerialPort:
     """Mock serial port for testing.
@@ -1545,3 +1558,171 @@ esp32:
 
     captured = capfd.readouterr()
     assert "Rename failed" in captured.out
+
+
+def test_command_update_all_path_string_conversion(
+    tmp_path: Path,
+    mock_run_external_process: Mock,
+    capfd: CaptureFixture[str],
+) -> None:
+    """Test that command_update_all properly converts Path objects to strings in output."""
+    yaml1 = tmp_path / "device1.yaml"
+    yaml1.write_text("""
+esphome:
+  name: device1
+
+esp32:
+  board: nodemcu-32s
+""")
+
+    yaml2 = tmp_path / "device2.yaml"
+    yaml2.write_text("""
+esphome:
+  name: device2
+
+esp8266:
+  board: nodemcuv2
+""")
+
+    setup_core(tmp_path=tmp_path)
+    mock_run_external_process.return_value = 0
+
+    assert command_update_all(MockArgs(configuration=[str(tmp_path)])) == 0
+
+    captured = capfd.readouterr()
+    clean_output = strip_ansi_codes(captured.out)
+
+    # Check that Path objects were properly converted to strings
+    # The output should contain file paths without causing TypeError
+    assert "device1.yaml" in clean_output
+    assert "device2.yaml" in clean_output
+    assert "SUCCESS" in clean_output
+    assert "SUMMARY" in clean_output
+
+    # Verify run_external_process was called for each file
+    assert mock_run_external_process.call_count == 2
+
+
+def test_command_update_all_with_failures(
+    tmp_path: Path,
+    mock_run_external_process: Mock,
+    capfd: CaptureFixture[str],
+) -> None:
+    """Test command_update_all handles mixed success/failure cases properly."""
+    yaml1 = tmp_path / "success_device.yaml"
+    yaml1.write_text("""
+esphome:
+  name: success_device
+
+esp32:
+  board: nodemcu-32s
+""")
+
+    yaml2 = tmp_path / "failed_device.yaml"
+    yaml2.write_text("""
+esphome:
+  name: failed_device
+
+esp8266:
+  board: nodemcuv2
+""")
+
+    setup_core(tmp_path=tmp_path)
+
+    # Mock mixed results - first succeeds, second fails
+    mock_run_external_process.side_effect = [0, 1]
+
+    # Should return 1 (failure) since one device failed
+    assert command_update_all(MockArgs(configuration=[str(tmp_path)])) == 1
+
+    captured = capfd.readouterr()
+    clean_output = strip_ansi_codes(captured.out)
+
+    # Check that both success and failure are properly displayed
+    assert "SUCCESS" in clean_output
+    assert "ERROR" in clean_output or "FAILED" in clean_output
+    assert "SUMMARY" in clean_output
+
+    # Files are processed in alphabetical order, so we need to check which one succeeded/failed
+    # The mock_run_external_process.side_effect = [0, 1] applies to files in alphabetical order
+    # So "failed_device.yaml" gets 0 (success) and "success_device.yaml" gets 1 (failure)
+    assert "failed_device.yaml: SUCCESS" in clean_output
+    assert "success_device.yaml: FAILED" in clean_output
+
+
+def test_command_update_all_empty_directory(
+    tmp_path: Path,
+    mock_run_external_process: Mock,
+    capfd: CaptureFixture[str],
+) -> None:
+    """Test command_update_all with an empty directory (no YAML files)."""
+    setup_core(tmp_path=tmp_path)
+
+    assert command_update_all(MockArgs(configuration=[str(tmp_path)])) == 0
+    mock_run_external_process.assert_not_called()
+
+    captured = capfd.readouterr()
+    clean_output = strip_ansi_codes(captured.out)
+
+    assert "SUMMARY" in clean_output
+
+
+def test_command_update_all_single_file(
+    tmp_path: Path,
+    mock_run_external_process: Mock,
+    capfd: CaptureFixture[str],
+) -> None:
+    """Test command_update_all with a single YAML file specified."""
+    yaml_file = tmp_path / "single_device.yaml"
+    yaml_file.write_text("""
+esphome:
+  name: single_device
+
+esp32:
+  board: nodemcu-32s
+""")
+
+    setup_core(tmp_path=tmp_path)
+    mock_run_external_process.return_value = 0
+
+    assert command_update_all(MockArgs(configuration=[str(yaml_file)])) == 0
+
+    captured = capfd.readouterr()
+    clean_output = strip_ansi_codes(captured.out)
+
+    assert "single_device.yaml" in clean_output
+    assert "SUCCESS" in clean_output
+    mock_run_external_process.assert_called_once()
+
+
+def test_command_update_all_path_formatting_in_color_calls(
+    tmp_path: Path,
+    mock_run_external_process: Mock,
+    capfd: CaptureFixture[str],
+) -> None:
+    """Test that Path objects are properly converted when passed to color() function."""
+    yaml_file = tmp_path / "test-device_123.yaml"
+    yaml_file.write_text("""
+esphome:
+  name: test-device_123
+
+esp32:
+  board: nodemcu-32s
+""")
+
+    setup_core(tmp_path=tmp_path)
+    mock_run_external_process.return_value = 0
+
+    assert command_update_all(MockArgs(configuration=[str(tmp_path)])) == 0
+
+    captured = capfd.readouterr()
+    clean_output = strip_ansi_codes(captured.out)
+
+    assert "test-device_123.yaml" in clean_output
+    assert "Updating" in clean_output
+    assert "SUCCESS" in clean_output
+    assert "SUMMARY" in clean_output
+
+    # Should not have any Python error messages
+    assert "TypeError" not in clean_output
+    assert "can only concatenate str" not in clean_output