diff --git a/BarcodeXlsx/BarcodeXlsx.csproj b/BarcodeXlsx/BarcodeXlsx.csproj
index 31679f0..06f2c49 100644
--- a/BarcodeXlsx/BarcodeXlsx.csproj
+++ b/BarcodeXlsx/BarcodeXlsx.csproj
@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>netcoreapp2.2</TargetFramework>
+    <TargetFramework>netcoreapp2.1</TargetFramework>
     <ApplicationIcon />
     <Win32Resource />
     <StartupObject />
diff --git a/Common/Common.csproj b/Common/Common.csproj
index 2f05e57..ca195b8 100644
--- a/Common/Common.csproj
+++ b/Common/Common.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>netcoreapp2.2</TargetFramework>
+    <TargetFramework>netcoreapp2.1</TargetFramework>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/barcode/Startup.cs b/barcode/Startup.cs
index ab915a7..ca88f60 100644
--- a/barcode/Startup.cs
+++ b/barcode/Startup.cs
@@ -32,7 +32,7 @@
             });
 
 
-            services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2);
+            services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
         }
 
         // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
diff --git a/barcode/app.yaml b/barcode/app.yaml
new file mode 100644
index 0000000..aa82a92
--- /dev/null
+++ b/barcode/app.yaml
@@ -0,0 +1,17 @@
+runtime: aspnetcore
+env: flex
+
+# This sample incurs costs to run on the App Engine flexible environment. 
+# The settings below are to reduce costs during testing and are not appropriate
+# for production use. For more information, see:
+# https://cloud.google.com/appengine/docs/flexible/python/configuring-your-app-with-app-yaml
+manual_scaling:
+  instances: 1
+resources:
+  cpu: 1
+  memory_gb: 0.5
+  disk_size_gb: 10
+
+env_variables:
+  # The __ in My__Greeting will be translated to a : by ASP.NET.
+  My__Greeting: Hello AppEngine!
diff --git a/barcode/barcode.csproj b/barcode/barcode.csproj
index aa6c24a..f75e275 100644
--- a/barcode/barcode.csproj
+++ b/barcode/barcode.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk.Web">
 
   <PropertyGroup>
-    <TargetFramework>netcoreapp2.2</TargetFramework>
+    <TargetFramework>netcoreapp2.1</TargetFramework>
     <AspNetCoreHostingModel>InProcess</AspNetCoreHostingModel>
     <DockerDefaultTargetOS>Windows</DockerDefaultTargetOS>
     <UserSecretsId>48b2a1da-1f8e-4230-b5f8-5dd9d113a1a6</UserSecretsId>