diff --git a/web/source/panels/lib/oauth.js b/web/source/panels/lib/oauth.js
index 9cbf3d484..3619dfa01 100644
--- a/web/source/panels/lib/oauth.js
+++ b/web/source/panels/lib/oauth.js
@@ -184,6 +184,12 @@ module.exports = function oauthClient(config, initState) {
 			} else {
 				return json;
 			}
+		}).catch(e => {
+			if (e instanceof SyntaxError) {
+				throw new Error("Error: The GtS API returned a non-json error. This usually means a network problem, or an issue with your instance's reverse proxy configuration.", {cause: e});
+			} else {
+				throw e;
+			}
 		});
 	}