diff --git a/.github/workflows/android.yml b/.github/workflows/android.yml
index 85c083b61..b91e82198 100644
--- a/.github/workflows/android.yml
+++ b/.github/workflows/android.yml
@@ -13,7 +13,7 @@ on:
 env:
   CCACHE_DIR: ${{ github.workspace }}/ccache_dir
   GITHUB_TOKEN: ${{ github.token }}
-  xcodeVersion: "16.2"  # Only affects Mac runners, and only for prerequisites.
+  xcodeVersion: "16.4"  # Only affects Mac runners, and only for prerequisites.
 
 concurrency:
   group: ${{ github.workflow }}-${{ github.event_name }}-${{ github.head_ref || github.ref }}
@@ -57,7 +57,7 @@ jobs:
         - os: ubuntu-22.04
           architecture: arm64
         # Do not attempt to use x64 on Mac.
-        - os: macos-14
+        - os: macos-15
           architecture: x64
     steps:
       - uses: lukka/get-cmake@latest
diff --git a/.github/workflows/cpp-packaging.yml b/.github/workflows/cpp-packaging.yml
index 585e8f591..ea53463b9 100644
--- a/.github/workflows/cpp-packaging.yml
+++ b/.github/workflows/cpp-packaging.yml
@@ -32,9 +32,9 @@ env:
   demumbleVer: "df938e45c2b0e064fb5323d88b692d03b451d271"
   # Use SHA256 for hashing files.
   hashCommand: "sha256sum"
-  # Xcode version 16.2 is the version we build the SDK with.
+  # Xcode version 16.4 is the version we build the SDK with.
   # Our MacOS runners will use the version in /Applications/Xcode_${xcodeVersion}.app
-  xcodeVersion: "16.2"
+  xcodeVersion: "16.4"
   # LLVM version with ARM MachO support has no version number yet.
   llvmVer: "5f187f0afaad33013ba03454c4749d99b1362534"
   GITHUB_TOKEN: ${{ github.token }}
@@ -79,13 +79,13 @@ jobs:
     if: ${{ github.event.inputs.downloadPublicVersion == '' && github.event.inputs.downloadPreviousRun == '' }}
     strategy:
       matrix:
-        os: [ubuntu-22.04, macos-14]
+        os: [ubuntu-22.04, macos-15]
         include:
         - os: ubuntu-22.04
           tools_platform: linux
           # Binutils 2.35.1 released Sep 19, 2020
           binutils_version: "2.35.1"
-        - os: macos-14
+        - os: macos-15
           tools_platform: darwin
           # Binutils 2.35.1 released Sep 19, 2020
           binutils_version: "2.35.1"
@@ -188,7 +188,7 @@ jobs:
 
   build_and_package_ios_tvos:
     name: build-and-package-ios-tvos
-    runs-on: macos-14
+    runs-on: macos-15
     if: ${{ github.event.inputs.downloadPublicVersion == '' && github.event.inputs.downloadPreviousRun == '' }}
     steps:
       - uses: lukka/get-cmake@latest
@@ -317,7 +317,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [windows-latest, ubuntu-22.04, macos-14]
+        os: [windows-latest, ubuntu-22.04, macos-15]
         build_type: ["Release", "Debug"]
         architecture: ["x64", "x86", "arm64"]
         msvc_runtime: ["static", "dynamic"]
@@ -335,7 +335,7 @@ jobs:
           vcpkg_triplet_suffix: "linux"
           additional_build_flags: ""
           sdk_platform: "linux"
-        - os: macos-14
+        - os: macos-15
           vcpkg_triplet_suffix: "osx"
           additional_build_flags: "--target_format libraries"
           sdk_platform: "darwin"
@@ -343,13 +343,13 @@ jobs:
         exclude:
         - os: windows-latest
           linux_abi: "c++11"
-        - os: macos-14
+        - os: macos-15
           architecture: "x86"
-        - os: macos-14
+        - os: macos-15
           msvc_runtime: "dynamic"
-        - os: macos-14
+        - os: macos-15
           linux_abi: "c++11"
-        - os: macos-14
+        - os: macos-15
           build_type: "Debug"
         - os: ubuntu-22.04
           msvc_runtime: "dynamic"
@@ -504,7 +504,7 @@ jobs:
           suffix: '-x64-Debug-dynamic'
           runs_on_platform: ubuntu-22.04
         - sdk_platform: darwin
-          runs_on_platform: macos-14
+          runs_on_platform: macos-15
         exclude:
         - sdk_platform: windows
           suffix: ''
diff --git a/.github/workflows/desktop.yml b/.github/workflows/desktop.yml
index 5aad61c38..9d532ff34 100644
--- a/.github/workflows/desktop.yml
+++ b/.github/workflows/desktop.yml
@@ -72,12 +72,12 @@ jobs:
           # msvc_runtime excludes
           - os: ubuntu-22.04
             msvc_runtime: "dynamic"
-          - os: macos-14
+          - os: macos-15
             msvc_runtime: "dynamic"
           # architecture excluees
-          - os: macos-14
+          - os: macos-15
             architecture: "x86"
-          - os: macos-14
+          - os: macos-15
             architecture: "x64"
           # Xcode excludes -- allow only one on osx and linux
           - os: ubuntu-22.04
diff --git a/.github/workflows/integration_tests.yml b/.github/workflows/integration_tests.yml
index 81db849f9..d034d008a 100644
--- a/.github/workflows/integration_tests.yml
+++ b/.github/workflows/integration_tests.yml
@@ -21,7 +21,7 @@ on:
         required: true
       operating_systems:
         description: 'CSV of VMs to run on'
-        default: 'ubuntu-22.04,windows-latest,macos-14'
+        default: 'ubuntu-22.04,windows-latest,macos-15'
         required: true
       desktop_ssl_variants:
         description: 'CSV of desktop SSL variants to use'
@@ -49,7 +49,7 @@ env:
   triggerLabelFull: "tests-requested: full"
   triggerLabelQuick: "tests-requested: quick"
   pythonVersion: '3.8'
-  xcodeVersion: '16.2'
+  xcodeVersion: '16.4'
   logArtifactRetentionDays: 90
   binaryArtifactRetentionDays: 7
   GITHUB_TOKEN: ${{ github.token }}
@@ -200,7 +200,7 @@ jobs:
           # at 3am PST/4am PDT. Running firestore desktop integration test aginst tip-of-tree ios repo
           echo "::warning ::Running against Firestore tip-of-tree"
           matrix_platform="Desktop"
-          matrix_os=$( python scripts/gha/print_matrix_configuration.py -w integration_tests ${TEST_MATRIX_PARAM} -k os -o "ubuntu-22.04,macos-14")
+          matrix_os=$( python scripts/gha/print_matrix_configuration.py -w integration_tests ${TEST_MATRIX_PARAM} -k os -o "ubuntu-22.04,macos-15")
         else
           matrix_platform=$( python scripts/gha/print_matrix_configuration.py -w integration_tests ${TEST_MATRIX_PARAM} -k platform -o "${{github.event.inputs.platforms}}" --apis ${apis} )
           matrix_os=$( python scripts/gha/print_matrix_configuration.py -w integration_tests ${TEST_MATRIX_PARAM} -k os -o "${{github.event.inputs.operating_systems}}")
@@ -267,7 +267,7 @@ jobs:
         - os: ubuntu-22.04
           arch: arm64
         # Do not attempt to use x86 on Mac.
-        - os: macos-14
+        - os: macos-15
           arch: x86
         # Until we support building openssl from source, we can't use the
         # system's openssl when cross-compiling, except on Linux. Builds on Linux
@@ -276,7 +276,7 @@ jobs:
         - os: windows-latest
           ssl_variant: openssl
           arch: x86
-        - os: macos-14
+        - os: macos-15
           ssl_variant: openssl
           arch: x64
     steps:
@@ -538,7 +538,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [macos-14]
+        os: [macos-15]
     steps:
       - uses: lukka/get-cmake@latest
         with:
@@ -646,7 +646,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [macos-14]
+        os: [macos-15]
     steps:
       - uses: lukka/get-cmake@latest
         with:
@@ -766,7 +766,7 @@ jobs:
         - os: ubuntu-22.04
           arch: arm64
         # Do not attempt to use x86 on Mac.
-        - os: macos-14
+        - os: macos-15
           arch: x86
         # Until we support building openssl from source, we can't use the
         # system's openssl when cross-compiling, except on Linux. Builds on Linux
@@ -775,7 +775,7 @@ jobs:
         - os: windows-latest
           ssl_variant: openssl
           arch: x86
-        - os: macos-14
+        - os: macos-15
           ssl_variant: openssl
           arch: x64
     steps:
@@ -1007,7 +1007,7 @@ jobs:
   test_ios:
     name: test-ios-${{ matrix.build_os }}-${{ matrix.ios_device }}-${{ matrix.test_type }}
     needs: [check_and_prepare, build_ios]
-    runs-on: macos-14
+    runs-on: macos-15
     if: contains(needs.check_and_prepare.outputs.matrix_platform, 'iOS') && needs.check_and_prepare.outputs.apis != '' && !cancelled()
     strategy:
       fail-fast: false
@@ -1021,7 +1021,7 @@ jobs:
              test_type: "uitest"
           -  ios_device: "ios_latest"
              test_type: "uitest"
-        build_os: [macos-14]
+        build_os: [macos-15]
     steps:
       - uses: actions/checkout@v3
         with:
@@ -1186,13 +1186,13 @@ jobs:
   test_tvos:
     name: test-tvos-${{ matrix.build_os }}-${{ matrix.tvos_device }}
     needs: [check_and_prepare, build_tvos]
-    runs-on: macos-14
+    runs-on: macos-15
     if: contains(needs.check_and_prepare.outputs.matrix_platform, 'tvOS') && needs.check_and_prepare.outputs.apis != '' && !cancelled()
     strategy:
       fail-fast: false
       matrix:
         tvos_device: ${{ fromJson(needs.check_and_prepare.outputs.tvos_device) }}
-        build_os: [macos-14]
+        build_os: [macos-15]
     steps:
       - uses: actions/checkout@v3
         with:
diff --git a/.github/workflows/ios.yml b/.github/workflows/ios.yml
index 7dabccfe1..de8b4d9f9 100644
--- a/.github/workflows/ios.yml
+++ b/.github/workflows/ios.yml
@@ -41,7 +41,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ 'macos-14' ]
+        os: [ 'macos-15' ]
         xcode_version: ${{ fromJson(needs.prepare_matrix.outputs.matrix_xcode_version) }}
     steps:
       - uses: lukka/get-cmake@latest
diff --git a/.github/workflows/update-dependencies.yml b/.github/workflows/update-dependencies.yml
index ab4f2817c..b6b7e6e9c 100644
--- a/.github/workflows/update-dependencies.yml
+++ b/.github/workflows/update-dependencies.yml
@@ -27,7 +27,7 @@ env:
 jobs:
   update_dependencies:
     name: update-deps
-    runs-on: macos-14
+    runs-on: macos-15
     steps:
       - name: Get token for firebase-workflow-trigger
         uses: tibdex/github-app-token@v1
diff --git a/cmake/external/firestore.cmake b/cmake/external/firestore.cmake
index 855b0b25f..aab233d1a 100644
--- a/cmake/external/firestore.cmake
+++ b/cmake/external/firestore.cmake
@@ -21,7 +21,7 @@ endif()
 # If the format of the line below changes, then be sure to update
 # https://github.com/firebase/firebase-cpp-sdk/blob/fd054fa016/.github/workflows/update-dependencies.yml#L81
 #set(version CocoaPods-11.8.1)
-set(version CocoaPods-12.2.0)
+set(version CocoaPods-12.4.0)
 
 function(GetReleasedDep)
   message("Getting released firebase-ios-sdk @ ${version}")
diff --git a/cmake/external/zlib.cmake b/cmake/external/zlib.cmake
index 595d14987..08111cae0 100644
--- a/cmake/external/zlib.cmake
+++ b/cmake/external/zlib.cmake
@@ -22,9 +22,8 @@ ExternalProject_Add(
   zlib
 
   DOWNLOAD_DIR ${FIREBASE_DOWNLOAD_DIR}
-  DOWNLOAD_NAME zlib-v1.2.11.tar.gz
-  URL https://github.com/madler/zlib/archive/v1.2.11.tar.gz
-  URL_HASH SHA256=629380c90a77b964d896ed37163f5c3a34f6e6d897311f1df2a7016355c45eff
+  DOWNLOAD_NAME zlib-v1.3.1.tar.gz
+  URL https://github.com/madler/zlib/archive/v1.3.1.tar.gz
 
   PREFIX ${PROJECT_BINARY_DIR}
 
diff --git a/release_build_files/readme.md b/release_build_files/readme.md
index 2f051dfcc..009789e70 100644
--- a/release_build_files/readme.md
+++ b/release_build_files/readme.md
@@ -408,7 +408,7 @@ Firebase Cloud Messaging (stub) | firebase_messaging.framework
 User Messaging Platform (stub)  | libfirebase_ump.a
 |                               | libfirebase_app.a
 
-The provided libraries have been tested using Xcode 16.2. When building C++
+The provided libraries have been tested using Xcode 16.4. When building C++
 desktop apps on OS X, you will need to link the `gssapi_krb5` and `pthread`
 system libraries, as well as the `CoreFoundation`, `Foundation`, `GSS`, and
 `Security` OS X system frameworks (consult your compiler documentation for more
diff --git a/scripts/gha/print_matrix_configuration.py b/scripts/gha/print_matrix_configuration.py
index ca665c326..389730a85 100644
--- a/scripts/gha/print_matrix_configuration.py
+++ b/scripts/gha/print_matrix_configuration.py
@@ -73,35 +73,35 @@
 PARAMETERS = {
   "desktop": {
     "matrix": {
-      "os": ["ubuntu-22.04", "macos-14"],
+      "os": ["ubuntu-22.04", "macos-15"],
       "build_type": ["Release", "Debug"],
       "architecture": ["x64", "x86", "arm64"],
       "msvc_runtime": ["static","dynamic"],
-      "xcode_version": ["16.2"],
+      "xcode_version": ["16.4"],
       "python_version": ["3.8"],
 
       EXPANDED_KEY: {
-        "os": ["ubuntu-22.04", "macos-14", "windows-latest"],
-        "xcode_version": ["16.2"],
+        "os": ["ubuntu-22.04", "macos-15", "windows-latest"],
+        "xcode_version": ["16.4"],
       }
     }
   },
 
   "android": {
     "matrix": {
-      "os": ["ubuntu-22.04", "macos-14", "windows-latest"],
+      "os": ["ubuntu-22.04", "macos-15", "windows-latest"],
       "architecture": ["x64", "arm64"],
       "python_version": ["3.8"],
 
       EXPANDED_KEY: {
-        "os": ["ubuntu-22.04", "macos-14", "windows-latest"]
+        "os": ["ubuntu-22.04", "macos-15", "windows-latest"]
       }
     }
   },
 
   "integration_tests": {
     "matrix": {
-      "os": ["ubuntu-22.04", "macos-14", "windows-latest"],
+      "os": ["ubuntu-22.04", "macos-15", "windows-latest"],
       "platform": ["Desktop", "Android", "iOS", "tvOS"],
       "ssl_lib": ["openssl"],
       "android_device": ["android_target", "emulator_ftl_target"],
@@ -113,7 +113,7 @@
       "msvc_runtime": ["dynamic"],
       "cpp_compiler_windows": ["VisualStudio2019"],
       "cpp_compiler_linux": ["clang-11.0"],
-      "xcode_version": ["16.2"],  # only the first one is used
+      "xcode_version": ["16.4"],  # only the first one is used
       "ndk_version": ["r22b"],
       "platform_version": ["28"],
       "build_tools_version": ["28.0.3"],
@@ -141,10 +141,10 @@
 
   "ios": {
     "matrix": {
-      "xcode_version": ["16.2"],
+      "xcode_version": ["16.4"],
 
       EXPANDED_KEY: {
-        "xcode_version": ["16.2"]
+        "xcode_version": ["16.4"]
       }
     }
   },