diff --git a/README.md b/README.md
index fdd71ca1..6110ac17 100644
--- a/README.md
+++ b/README.md
@@ -58,14 +58,13 @@ Setup PHP with required extensions, php.ini configuration, code-coverage support
 
 |Virtual environment|YAML workflow label|Pre-installed PHP|
 |--- |--- |--- |
-|Ubuntu 16.04|`ubuntu-16.04`|`PHP 5.6` to `PHP 8.0`|
+|Ubuntu 16.04 [(deprecated)](https://setup-php.com/i/452)|`ubuntu-16.04`|`PHP 5.6` to `PHP 8.0`|
 |Ubuntu 18.04|`ubuntu-18.04`|`PHP 7.1` to `PHP 8.0`|
 |Ubuntu 20.04|`ubuntu-latest` or `ubuntu-20.04`|`PHP 7.4` to `PHP 8.0`|
 |Windows Server 2019|`windows-latest` or `windows-2019`|`PHP 8.0`|
 |macOS 10.15 Catalina|`macos-latest` or `macos-10.15`|`PHP 8.0`|
 |macOS 11.0 Big Sur|`macos-11.0`|`PHP 8.0`|
 
-
 ## :heavy_plus_sign: PHP Extension Support
 - On `ubuntu` by default extensions which are available as a package can be installed. If the extension is not available as a package but it is on `PECL`, it can be installed by specifying `pecl` in the tools input.
 - On `windows` extensions which have `windows` binary on `PECL` can be installed.
diff --git a/dist/index.js b/dist/index.js
index d85eeee9..c9037c80 100644
--- a/dist/index.js
+++ b/dist/index.js
@@ -444,6 +444,9 @@ async function run() {
             core.setFailed('PHP 8.1 is not supported on setup-php v1.\nPlease upgrade to v2 - https://setup-php.com/w/Switch-to-v2');
             return;
         }
+        if ((await utils.readEnv('ImageOS')) == 'ubuntu16') {
+            core.warning('Ubuntu 16.04 is deprecated.\nPlease upgrade to Ubuntu 18.04 or Ubuntu 20.04 - https://setup-php.com/i/452');
+        }
         if (version) {
             const os_version = process.platform;
             let script_path = '';
diff --git a/src/install.ts b/src/install.ts
index 29b8f38f..d036b0fc 100644
--- a/src/install.ts
+++ b/src/install.ts
@@ -67,6 +67,11 @@ export async function run(): Promise<void> {
       );
       return;
     }
+    if ((await utils.readEnv('ImageOS')) == 'ubuntu16') {
+      core.warning(
+        'Ubuntu 16.04 is deprecated.\nPlease upgrade to Ubuntu 18.04 or Ubuntu 20.04 - https://setup-php.com/i/452'
+      );
+    }
     if (version) {
       const os_version: string = process.platform;
       // check the os version and run the respective script