diff --git a/.github/workflows/build-linux.yml b/.github/workflows/build-linux.yml
index 87a0430f8..62b81bdf5 100644
--- a/.github/workflows/build-linux.yml
+++ b/.github/workflows/build-linux.yml
@@ -63,17 +63,17 @@ jobs:
 
           sudo apt install cmake build-essential pkg-config libpython-dev python-numpy
           
-          echo "::set-env name=BOOST_ROOT::$(echo $BOOST_ROOT_1_69_0)"
-          echo "::set-env name=LD_LIBRARY_PATH::$(echo $BOOST_ROOT_1_69_0/lib)"
+          echo "BOOST_ROOT=$(echo $BOOST_ROOT_1_69_0)" >> $GITHUB_ENV
+          echo "LD_LIBRARY_PATH=$(echo $BOOST_ROOT_1_69_0/lib)" >> $GITHUB_ENV
           
           if [ "${{ matrix.compiler }}" = "gcc" ]; then
             sudo apt-get install -y g++-${{ matrix.version }} g++-${{ matrix.version }}-multilib
-            echo "::set-env name=CC::gcc-${{ matrix.version }}"
-            echo "::set-env name=CXX::g++-${{ matrix.version }}"
+            echo "CC=gcc-${{ matrix.version }}" >> $GITHUB_ENV
+            echo "CXX=g++-${{ matrix.version }}" >> $GITHUB_ENV
           else
             sudo apt-get install -y clang-${{ matrix.version }} g++-multilib
-            echo "::set-env name=CC::clang-${{ matrix.version }}"
-            echo "::set-env name=CXX::clang++-${{ matrix.version }}"
+            echo "CC=clang-${{ matrix.version }}" >> $GITHUB_ENV
+            echo "CXX=clang++-${{ matrix.version }}" >> $GITHUB_ENV
           fi
       - name: Check Boost version
         if: runner.os == 'Linux'
diff --git a/.github/workflows/build-macos.yml b/.github/workflows/build-macos.yml
index 3ce98055a..69873980a 100644
--- a/.github/workflows/build-macos.yml
+++ b/.github/workflows/build-macos.yml
@@ -40,12 +40,12 @@ jobs:
           brew install ProfFan/robotics/boost
           if [ "${{ matrix.compiler }}" = "gcc" ]; then
             brew install gcc@${{ matrix.version }}
-            echo "::set-env name=CC::gcc-${{ matrix.version }}"
-            echo "::set-env name=CXX::g++-${{ matrix.version }}"
+            echo "CC=gcc-${{ matrix.version }}" >> $GITHUB_ENV
+            echo "CXX=g++-${{ matrix.version }}" >> $GITHUB_ENV
           else
             sudo xcode-select -switch /Applications/Xcode_${{ matrix.version }}.app
-            echo "::set-env name=CC::clang"
-            echo "::set-env name=CXX::clang++"
+            echo "CC=clang" >> $GITHUB_ENV
+            echo "CXX=clang++" >> $GITHUB_ENV
           fi
       - name: Build and Test (macOS)
         if: runner.os == 'macOS'
diff --git a/.github/workflows/build-python.yml b/.github/workflows/build-python.yml
index 8255fb8ab..97b68f6b7 100644
--- a/.github/workflows/build-python.yml
+++ b/.github/workflows/build-python.yml
@@ -77,12 +77,12 @@ jobs:
           
           if [ "${{ matrix.compiler }}" = "gcc" ]; then
             sudo apt-get install -y g++-${{ matrix.version }} g++-${{ matrix.version }}-multilib
-            echo "::set-env name=CC::gcc-${{ matrix.version }}"
-            echo "::set-env name=CXX::g++-${{ matrix.version }}"
+            echo "CC=gcc-${{ matrix.version }}" >> $GITHUB_ENV
+            echo "CXX=g++-${{ matrix.version }}" >> $GITHUB_ENV
           else
             sudo apt-get install -y clang-${{ matrix.version }} g++-multilib
-            echo "::set-env name=CC::clang-${{ matrix.version }}"
-            echo "::set-env name=CXX::clang++-${{ matrix.version }}"
+            echo "CC=clang-${{ matrix.version }}" >> $GITHUB_ENV
+            echo "CXX=clang++-${{ matrix.version }}" >> $GITHUB_ENV
           fi
       - name: Install (macOS)
         if: runner.os == 'macOS'
@@ -92,17 +92,17 @@ jobs:
           brew install ProfFan/robotics/boost
           if [ "${{ matrix.compiler }}" = "gcc" ]; then
             brew install gcc@${{ matrix.version }}
-            echo "::set-env name=CC::gcc-${{ matrix.version }}"
-            echo "::set-env name=CXX::g++-${{ matrix.version }}"
+            echo "CC=gcc-${{ matrix.version }}" >> $GITHUB_ENV
+            echo "CXX=g++-${{ matrix.version }}" >> $GITHUB_ENV
           else
             sudo xcode-select -switch /Applications/Xcode_${{ matrix.version }}.app
-            echo "::set-env name=CC::clang"
-            echo "::set-env name=CXX::clang++"
+            echo "CC=clang" >> $GITHUB_ENV
+            echo "CXX=clang++" >> $GITHUB_ENV
           fi
       - name: Set GTSAM_WITH_TBB Flag
         if: matrix.flag == 'tbb'
         run: |
-          echo "::set-env name=GTSAM_WITH_TBB::ON"
+          echo "GTSAM_WITH_TBB=ON" >> $GITHUB_ENV
           echo "GTSAM Uses TBB"
       - name: Build (Linux)
         if: runner.os == 'Linux'
diff --git a/.github/workflows/build-special.yml b/.github/workflows/build-special.yml
index c314acb16..70f3f40ec 100644
--- a/.github/workflows/build-special.yml
+++ b/.github/workflows/build-special.yml
@@ -64,17 +64,17 @@ jobs:
 
           sudo apt install cmake build-essential pkg-config libpython-dev python-numpy
 
-          echo "::set-env name=BOOST_ROOT::$(echo $BOOST_ROOT_1_69_0)"
-          echo "::set-env name=LD_LIBRARY_PATH::$(echo $BOOST_ROOT_1_69_0/lib)"
+          echo "BOOST_ROOT=$(echo $BOOST_ROOT_1_69_0)" >> $GITHUB_ENV
+          echo "LD_LIBRARY_PATH=$(echo $BOOST_ROOT_1_69_0/lib)" >> $GITHUB_ENV
 
           if [ "${{ matrix.compiler }}" = "gcc" ]; then
             sudo apt-get install -y g++-${{ matrix.version }} g++-${{ matrix.version }}-multilib
-            echo "::set-env name=CC::gcc-${{ matrix.version }}"
-            echo "::set-env name=CXX::g++-${{ matrix.version }}"
+            echo "CC=gcc-${{ matrix.version }}" >> $GITHUB_ENV
+            echo "CXX=g++-${{ matrix.version }}" >> $GITHUB_ENV
           else
             sudo apt-get install -y clang-${{ matrix.version }} g++-multilib
-            echo "::set-env name=CC::clang-${{ matrix.version }}"
-            echo "::set-env name=CXX::clang++-${{ matrix.version }}"
+            echo "CC=clang-${{ matrix.version }}" >> $GITHUB_ENV
+            echo "CXX=clang++-${{ matrix.version }}" >> $GITHUB_ENV
           fi
 
       - name: Install (macOS)
@@ -83,30 +83,30 @@ jobs:
           brew install cmake ninja boost
           if [ "${{ matrix.compiler }}" = "gcc" ]; then
             brew install gcc@${{ matrix.version }}
-            echo "::set-env name=CC::gcc-${{ matrix.version }}"
-            echo "::set-env name=CXX::g++-${{ matrix.version }}"
+            echo "CC=gcc-${{ matrix.version }}" >> $GITHUB_ENV
+            echo "CXX=g++-${{ matrix.version }}" >> $GITHUB_ENV
           else
             sudo xcode-select -switch /Applications/Xcode_${{ matrix.version }}.app
-            echo "::set-env name=CC::clang"
-            echo "::set-env name=CXX::clang++"
+            echo "CC=clang" >> $GITHUB_ENV
+            echo "CXX=clang++" >> $GITHUB_ENV
             fi
 
       - name: Set Allow Deprecated Flag
         if: matrix.flag == 'deprecated'
         run: |
-          echo "::set-env name=GTSAM_ALLOW_DEPRECATED_SINCE_V41::ON"
+          echo "GTSAM_ALLOW_DEPRECATED_SINCE_V41=ON" >> $GITHUB_ENV
           echo "Allow deprecated since version 4.1"
 
       - name: Set Use Quaternions Flag
         if: matrix.flag == 'quaternions'
         run: |
-          echo "::set-env name=GTSAM_USE_QUATERNIONS::ON"
+          echo "GTSAM_USE_QUATERNIONS=ON" >> $GITHUB_ENV
           echo "Use Quaternions for rotations"
 
       - name: Set GTSAM_WITH_TBB Flag
         if: matrix.flag == 'tbb'
         run: |
-          echo "::set-env name=GTSAM_WITH_TBB::ON"
+          echo "GTSAM_WITH_TBB=ON" >> $GITHUB_ENV
           echo "GTSAM Uses TBB"
 
       - name: Build & Test
diff --git a/.github/workflows/build-windows.yml b/.github/workflows/build-windows.yml
index b3150a751..432f7490d 100644
--- a/.github/workflows/build-windows.yml
+++ b/.github/workflows/build-windows.yml
@@ -50,17 +50,17 @@ jobs:
             # See: https://github.com/DaanDeMeyer/doctest/runs/231595515
             # See: https://github.community/t5/GitHub-Actions/Something-is-wrong-with-the-chocolatey-installed-version-of-gcc/td-p/32413
             scoop install gcc --global
-            echo "::set-env name=CC::gcc"
-            echo "::set-env name=CXX::g++"
+            echo "CC=gcc" >> $GITHUB_ENV
+            echo "CXX=g++" >> $GITHUB_ENV
           } elseif ("${{ matrix.compiler }}" -eq "clang") {
-            echo "::set-env name=CC::clang"
-            echo "::set-env name=CXX::clang++"
+            echo "CC=clang" >> $GITHUB_ENV
+            echo "CXX=clang++" >> $GITHUB_ENV
           } else {
-            echo "::set-env name=CC::${{ matrix.compiler }}"
-            echo "::set-env name=CXX::${{ matrix.compiler }}"
+            echo "CC=${{ matrix.compiler }}" >> $GITHUB_ENV
+            echo "CXX=${{ matrix.compiler }}" >> $GITHUB_ENV
           }
           # Scoop modifies the PATH so we make the modified PATH global.
-          echo "::set-env name=PATH::$env:PATH"
+          echo "$env" >> $GITHUB_PATH
       - name: Build (Windows)
         if: runner.os == 'Windows'
         run: |