diff --git a/src/apphealthmonitor.js b/src/apphealthmonitor.js
index 4f8fc8989..7ccb7cacf 100644
--- a/src/apphealthmonitor.js
+++ b/src/apphealthmonitor.js
@@ -95,8 +95,10 @@ async function checkAppHealth(app, options) {
         .timeout(options.timeout * 1000));
 
     if (healthCheckError) {
+        await apps.appendLogLine(app, `=> Healtheck error: ${healthCheckError}`);
         await setHealth(app, apps.HEALTH_UNHEALTHY);
     } else if (response.status > 403) { // 2xx and 3xx are ok. even 401 and 403 are ok for now (for WP sites)
+        await apps.appendLogLine(app, `=> Healtheck error got response status ${response.status}`);
         await setHealth(app, apps.HEALTH_UNHEALTHY);
     } else {
         await setHealth(app, apps.HEALTH_HEALTHY);
diff --git a/src/apps.js b/src/apps.js
index 7aff191bc..8dc0f63d2 100644
--- a/src/apps.js
+++ b/src/apps.js
@@ -61,6 +61,8 @@ exports = module.exports = {
     getLogPaths,
     getLogs,
 
+    appendLogLine,
+
     getCertificate,
 
     start,
@@ -2013,6 +2015,16 @@ async function getLogs(app, options) {
     return transformStream;
 }
 
+// never fails just prints error
+async function appendLogLine(app, line) {
+    assert.strictEqual(typeof app, 'object');
+    assert.strictEqual(typeof line, 'string');
+
+    const logFilePath = path.join(paths.LOG_DIR, app.id, 'app.log');
+
+    if (!safe.fs.appendFileSync(logFilePath, line)) console.error(`Could not append log line for app ${app.id} at ${logFilePath}: ${safe.error.message}`);
+}
+
 async function getCertificate(subdomain, domain) {
     assert.strictEqual(typeof subdomain, 'string');
     assert.strictEqual(typeof domain, 'string');