diff --git a/eng/pipelines/templates/jobs/archetype-sdk-client.yml b/eng/pipelines/templates/jobs/archetype-sdk-client.yml
index e5f35145e..037206a95 100644
--- a/eng/pipelines/templates/jobs/archetype-sdk-client.yml
+++ b/eng/pipelines/templates/jobs/archetype-sdk-client.yml
@@ -26,6 +26,15 @@ jobs:
   condition: and(succeededOrFailed(), ne(variables['Skip.Test'], 'true'))
   strategy:
     matrix:
+      Linux_x64_gcc5:
+        Pool: azsdk-pool-mms-ubuntu-1804-general
+        OSVmImage: MMSUbuntu18.04
+        VcpkgInstall: 'curl[ssl] libxml2 openssl'
+        VCPKG_DEFAULT_TRIPLET: 'x64-linux'
+        # Can't set CC and CXX to env because it would affect VCPKG building which requires g++ > 7
+        # So, this conf will set the CXX for cmake inline.
+        CmakeEnvArg: 'CC=/usr/bin/gcc-5 CXX=/usr/bin/g++-5 cmake'
+        BuildArgs: '-j 4'
       Linux_x64_gcc8:
         Pool: azsdk-pool-mms-ubuntu-1804-general
         OSVmImage: MMSUbuntu18.04
@@ -138,6 +147,10 @@ jobs:
     value: "xml"
   - name: BuildArgs
     value: ""
+  - name: CmakeEnvArg
+    value: ""
+  - name: CmakeArgs
+    value: ""
 
   steps:
   - checkout: self
@@ -147,6 +160,26 @@ jobs:
     parameters:
       AgentImage: $(OSVmImage)
 
+  # Add g++5 repo to ubuntu
+  - bash: sudo sh -c "echo 'deb http://ftp.debian.org/debian/ stretch main' >> /etc/apt/sources.list"
+    displayName: Add g++ 5
+    condition: >-
+      and(
+        succeeded(), 
+        contains(variables['OSVmImage'], 'Ubuntu'), 
+        contains(variables['CmakeEnvArg'], 'CC=/usr/bin/gcc-5 CXX=/usr/bin/g++-5 cmake')
+      )
+
+  # Install g++5
+  - bash: sudo apt-get update & sudo apt-get install g++-5
+    displayName: Install g++ 5
+    condition: >-
+      and(
+        succeeded(), 
+        contains(variables['OSVmImage'], 'Ubuntu'), 
+        contains(variables['CmakeEnvArg'], 'CC=/usr/bin/gcc-5 CXX=/usr/bin/g++-5 cmake')
+      )
+
   # Install gcc and g++ 8 if it is needed on the image.
   - bash: sudo apt-get install gcc-8 g++-8 -y
     displayName: Install gcc and g++ 8
@@ -211,6 +244,7 @@ jobs:
     parameters:
       GenerateArgs: "$(CmakeArgs)"
       BuildArgs: "$(BuildArgs)"
+      Env: "$(CmakeEnvArg)"
 
   - script: ctest -C Debug -V --tests-regex ${{ parameters.CtestRegex }}
     workingDirectory: build
diff --git a/eng/pipelines/templates/jobs/archetype-sdk-tests.yml b/eng/pipelines/templates/jobs/archetype-sdk-tests.yml
index 9a6735a20..8a5cf42e4 100644
--- a/eng/pipelines/templates/jobs/archetype-sdk-tests.yml
+++ b/eng/pipelines/templates/jobs/archetype-sdk-tests.yml
@@ -27,6 +27,16 @@ jobs:
   timeoutInMinutes: ${{ parameters.TimeoutInMinutes }}
   strategy:
     matrix:
+      Linux_x64_gcc5_with_unit_test:
+        Pool: azsdk-pool-mms-ubuntu-1804-general
+        OSVmImage: MMSUbuntu18.04
+        VcpkgInstall: 'curl[ssl] libxml2 openssl'
+        VCPKG_DEFAULT_TRIPLET: 'x64-linux'
+        # Can't set CC and CXX to env because it would affect VCPKG building which requires g++ > 7
+        # So, this conf will set the CXX for cmake inline.
+        CmakeEnvArg: 'CC=/usr/bin/gcc-5 CXX=/usr/bin/g++-5 cmake'
+        BuildArgs: '-j 4'
+        CmakeArgs: ' -DBUILD_TESTING=ON -DRUN_LONG_UNIT_TESTS=ON'
       Linux_x64_with_unit_test:
         Pool: azsdk-pool-mms-ubuntu-1804-general
         OSVmImage: MMSUbuntu18.04
@@ -105,6 +115,9 @@ jobs:
     CMOCKA_MESSAGE_OUTPUT: "xml"
     AZURE_ENABLE_STATIC_ANALYSIS: 1
     AZURE_KEYVAULT_AVOID_THROTTLED: 1
+    BuildArgs: ""
+    CmakeEnvArg: ""
+    CmakeArgs: ""    
 
   steps:
   - checkout: self
@@ -116,6 +129,26 @@ jobs:
 
   - template: /eng/common/pipelines/templates/steps/bypass-local-dns.yml
 
+  # Add g++5 repo to ubuntu
+  - bash: sudo sh -c "echo 'deb http://ftp.debian.org/debian/ stretch main' >> /etc/apt/sources.list"
+    displayName: Add g++ 5
+    condition: >-
+      and(
+        succeeded(), 
+        contains(variables['OSVmImage'], 'Ubuntu'), 
+        contains(variables['CmakeEnvArg'], 'CC=/usr/bin/gcc-5 CXX=/usr/bin/g++-5 cmake')
+      )
+
+  # Install g++5
+  - bash: sudo apt-get update & sudo apt-get install g++-5
+    displayName: Install g++ 5
+    condition: >-
+      and(
+        succeeded(), 
+        contains(variables['OSVmImage'], 'Ubuntu'), 
+        contains(variables['CmakeEnvArg'], 'CC=/usr/bin/gcc-5 CXX=/usr/bin/g++-5 cmake')
+      )
+
   # Install apt dependencies (if appropriate)
   - bash: sudo apt install -y $(AptDependencies)
     condition: and(succeededOrFailed(), ne(variables['AptDependencies'], ''))
@@ -137,6 +170,7 @@ jobs:
     parameters:
       GenerateArgs: $(CmakeArgs)
       BuildArgs: "$(BuildArgs)"
+      Env: "$(CmakeEnvArg)"
 
   - template: /eng/common/TestResources/deploy-test-resources.yml
     parameters:
diff --git a/eng/pipelines/templates/steps/cmake-build.yml b/eng/pipelines/templates/steps/cmake-build.yml
index 19d52cddd..a755a2b1e 100644
--- a/eng/pipelines/templates/steps/cmake-build.yml
+++ b/eng/pipelines/templates/steps/cmake-build.yml
@@ -1,4 +1,5 @@
 parameters:
+  Env: ''
   GenerateArgs: ''
   Build: true
   BuildArgs: ''
@@ -12,7 +13,7 @@ steps:
     workingDirectory: build
     displayName: cmake --version
 
-  - script: cmake ${{ parameters.GenerateArgs }} ..
+  - script: ${{ parameters.Env }} cmake ${{ parameters.GenerateArgs }} ..
     workingDirectory: build
     displayName: cmake generate
 
diff --git a/sdk/core/azure-core/CHANGELOG.md b/sdk/core/azure-core/CHANGELOG.md
index 8ffbc0866..287ae2f71 100644
--- a/sdk/core/azure-core/CHANGELOG.md
+++ b/sdk/core/azure-core/CHANGELOG.md
@@ -8,6 +8,8 @@
 
 ### Bugs Fixed
 
+- [2785](https://github.com/Azure/azure-sdk-for-cpp/issues/2785) Fix to build on g++ 5.5.
+
 ### Other Changes
 
 - Fixed compilation error on POSIX platforms where OpenSSL was not available.
diff --git a/sdk/core/azure-core/src/base64.cpp b/sdk/core/azure-core/src/base64.cpp
index 83924baea..784f4c3f9 100644
--- a/sdk/core/azure-core/src/base64.cpp
+++ b/sdk/core/azure-core/src/base64.cpp
@@ -64,7 +64,7 @@ namespace Azure { namespace Core {
     bio = BIO_push(BIO_new(BIO_f_base64()), bio);
     BIO_set_flags(bio, BIO_FLAGS_BASE64_NO_NL);
     BIO_write(bio, data.data(), static_cast<int>(data.size()));
-    BIO_flush(bio);
+    (void)BIO_flush(bio);
     BUF_MEM* bufferPtr;
     BIO_get_mem_ptr(bio, &bufferPtr);
     std::string toReturn(bufferPtr->data, bufferPtr->length);