diff --git a/.vscode/settings.json b/.vscode/settings.json
index 3b66410..57a849f 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -1,3 +1,4 @@
 {
-    "git.ignoreLimitWarning": true
+    "git.ignoreLimitWarning": true,
+    "deno.enable": false
 }
\ No newline at end of file
diff --git a/__tests__/set-tokens.test.ts b/__tests__/set-tokens.test.ts
index 1a7a743..d6c373c 100644
--- a/__tests__/set-tokens.test.ts
+++ b/__tests__/set-tokens.test.ts
@@ -63,7 +63,10 @@ describe('setGithubToken()', () => {
         'refs/heads/master',
         'push'
       );
-    }).toThrowError('GITHUB_TOKEN does not support to push to an external repository');
+    }).toThrowError(`\
+The generated GITHUB_TOKEN (github_token) does not support to push to an external repository.
+Use deploy_key or personal_token.
+`);
   });
 
   test('return remote url with GITHUB_TOKEN pull_request', () => {
diff --git a/package-lock.json b/package-lock.json
index 8fea418..8fa008e 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -6994,9 +6994,9 @@
       }
     },
     "lodash": {
-      "version": "4.17.15",
-      "resolved": "https://registry.npmjs.org/lodash/-/lodash-4.17.15.tgz",
-      "integrity": "sha512-8xOcRHvCjnocdS5cpwXQXVzmmh5e5+saE2QGoeQmbKmRS6J3VQppPOIt0MnmE+4xlZoumy0GPG0D0MVIQbNA1A==",
+      "version": "4.17.19",
+      "resolved": "https://registry.npmjs.org/lodash/-/lodash-4.17.19.tgz",
+      "integrity": "sha512-JNvd8XER9GQX0v2qJgsaN/mzFCNA5BRe/j8JN9d+tWyGLSodKQHKFicdwNYzWwI3wjRnaKPsGj1XkBjx/F96DQ==",
       "dev": true
     },
     "lodash._reinterpolate": {
diff --git a/src/set-tokens.ts b/src/set-tokens.ts
index 97a36dd..ab1e462 100644
--- a/src/set-tokens.ts
+++ b/src/set-tokens.ts
@@ -44,6 +44,11 @@ Host github
   await exec.exec('chmod', ['600', sshConfigPath]);
 
   if (process.platform === 'win32') {
+    core.warning(`\
+Currently, the deploy_key option is not supported on the windows-latest.
+Watch https://github.com/peaceiris/actions-gh-pages/issues/87
+`);
+
     await cpSpawnSync('Start-Process', ['powershell.exe', '-Verb', 'runas']);
     await cpSpawnSync('sh', ['-c', '\'eval "$(ssh-agent)"\''], {shell: true});
     await exec.exec('sc', ['config', 'ssh-agent', 'start=auto']);
@@ -71,7 +76,10 @@ export function setGithubToken(
   let isProhibitedBranch = false;
 
   if (externalRepository) {
-    throw new Error('GITHUB_TOKEN does not support to push to an external repository');
+    throw new Error(`\
+The generated GITHUB_TOKEN (github_token) does not support to push to an external repository.
+Use deploy_key or personal_token.
+`);
   }
 
   if (eventName === 'push') {