diff --git a/homeassistant/components/alarmdecoder/config_flow.py b/homeassistant/components/alarmdecoder/config_flow.py
index 74b23f049a7..a82b84b60d1 100644
--- a/homeassistant/components/alarmdecoder/config_flow.py
+++ b/homeassistant/components/alarmdecoder/config_flow.py
@@ -111,7 +111,7 @@ class AlarmDecoderFlowHandler(config_entries.ConfigFlow, domain=DOMAIN):
                     title=title, data={CONF_PROTOCOL: self.protocol, **connection}
                 )
             except NoDeviceError:
-                errors["base"] = "service_unavailable"
+                errors["base"] = "cannot_connect"
             except Exception:  # pylint: disable=broad-except
                 _LOGGER.exception("Unexpected exception during AlarmDecoder setup")
                 errors["base"] = "unknown"
diff --git a/homeassistant/components/alarmdecoder/strings.json b/homeassistant/components/alarmdecoder/strings.json
index ed250b92b98..33b33749048 100644
--- a/homeassistant/components/alarmdecoder/strings.json
+++ b/homeassistant/components/alarmdecoder/strings.json
@@ -18,7 +18,7 @@
       }
     },
     "error": {
-      "service_unavailable": "[%key:common::config_flow::error::cannot_connect%]"
+      "cannot_connect": "[%key:common::config_flow::error::cannot_connect%]"
     },
     "create_entry": { "default": "Successfully connected to AlarmDecoder." },
     "abort": {
diff --git a/tests/components/alarmdecoder/test_config_flow.py b/tests/components/alarmdecoder/test_config_flow.py
index 64f4a604ff3..4af8b783b07 100644
--- a/tests/components/alarmdecoder/test_config_flow.py
+++ b/tests/components/alarmdecoder/test_config_flow.py
@@ -126,7 +126,7 @@ async def test_setup_connection_error(hass: HomeAssistant):
             result["flow_id"], connection_settings
         )
         assert result["type"] == data_entry_flow.RESULT_TYPE_FORM
-        assert result["errors"] == {"base": "service_unavailable"}
+        assert result["errors"] == {"base": "cannot_connect"}
 
 
 async def test_options_arm_flow(hass: HomeAssistant):