diff --git a/src/jsonrpc2.ml b/src/jsonrpc2.ml
index aa578a70..e5245f88 100644
--- a/src/jsonrpc2.ml
+++ b/src/jsonrpc2.ml
@@ -144,6 +144,7 @@ module Make(IO : IO)
           try_ @@ fun () ->
           IO.return @@ J.from_string (Bytes.unsafe_to_string buf)
         in
+        Log.debug (fun k->k "got json %a" J.pp j);
         begin match Jsonrpc.Message.either_of_yojson j with
           | m -> IO.return @@ Ok m
           | exception _ ->
diff --git a/src/server.ml b/src/server.ml
index cb0d7094..968c2dd9 100644
--- a/src/server.ml
+++ b/src/server.ml
@@ -297,7 +297,9 @@ module Make(IO : IO) = struct
         | Lsp.Client_notification.TextDocumentDidChange {textDocument=doc; contentChanges=c} ->
           let notify_back = new notify_back ~uri:doc.uri ~notify_back () in
           begin match Hashtbl.find_opt docs doc.uri with
-            | None -> IO.failwith "unknown document"
+            | None ->
+              Log.err (fun k->k "unknown document: '%s'" doc.uri);
+              IO.failwith "unknown document"
             | Some st ->
               let old_content = st.content in
               let new_doc: Lsp.Text_document.t =