diff --git a/mirage/opam_file.ml b/mirage/opam_file.ml
index e08f252..1489523 100644
--- a/mirage/opam_file.ml
+++ b/mirage/opam_file.ml
@@ -13,17 +13,22 @@ let hex_of_string s =
 let decode_digest filename str =
   let hex h s =
     match hex_of_string s with
-    | Ok d -> Some (h, d)
-    | Error `Msg msg ->
-      Log.warn (fun m -> m "%s invalid hex (%s) %s" filename msg s); None
+    | Ok d -> Ok (h, d)
+    | Error `Msg msg as e ->
+      Log.warn (fun m -> m "%s invalid hex (%s) %s" filename msg s);
+      e
   in
   match String.split_on_char '=' str with
   | [ data ] -> hex `MD5 data
   | [ "md5" ; data ] -> hex `MD5 data
   | [ "sha256" ; data ] -> hex `SHA256 data
   | [ "sha512" ; data ] -> hex `SHA512 data
-  | [ hash ; _ ] -> Log.warn (fun m -> m "%s unknown hash %s" filename hash); None
-  | _ -> Log.warn (fun m -> m "%s unexpected hash format %S" filename str); None
+  | [ hash ; _ ] ->
+    Log.warn (fun m -> m "%s unknown hash %s" filename hash);
+    Error (`Msg ("unknown hash " ^ hash))
+  | _ ->
+    Log.warn (fun m -> m "%s unexpected hash format %S" filename str);
+    Error (`Msg ("unexpected hash format " ^ str))
 
 let extract_url_checksum filename items =
   let open OpamParserTypes.FullPos in
@@ -42,64 +47,73 @@ let extract_url_checksum filename items =
   in
   let url =
     match url, archive with
-    | Some { pelem = Variable (_, { pelem = String url ; _ }) ; _ }, None -> Some url
-    | None, Some { pelem = Variable (_, { pelem = String url ; _ }); _ } -> Some url
+    | Some { pelem = Variable (_, { pelem = String url ; _ }) ; _ }, None -> Ok url
+    | None, Some { pelem = Variable (_, { pelem = String url ; _ }); _ } -> Ok url
     | _ ->
-      Log.warn (fun m -> m "%s neither src nor archive present" filename); None
+      Log.warn (fun m -> m "%s neither src nor archive present" filename);
+      Error (`Msg "neither 'src' nor 'archive' present")
   in
-  let csum =
+  let csum, csum_errs =
     match checksum with
     | Some { pelem = Variable (_, { pelem = List { pelem = csums ; _ } ; _ }); _ } ->
-      let csums =
-        List.fold_left (fun acc ->
+      let csums, errs =
+        List.fold_left (fun (csums, errs) ->
             function
             | { pelem = String csum ; _ } ->
               begin match decode_digest filename csum with
-                | None -> acc
-                | Some (h, v) ->
+                | Error e -> csums, e :: errs
+                | Ok (h, v) ->
                   HM.update h (function
                       | None -> Some v
                       | Some v' when String.equal v v' -> None
                       | Some v' ->
                         Log.warn (fun m -> m "for %s, hash %s, multiple keys are present: %s %s"
-                                     (Option.value ~default:"NONE" url) (hash_to_string h) (Ohex.encode v) (Ohex.encode v'));
+                                     (Result.value ~default:"NONE" url) (hash_to_string h) (Ohex.encode v) (Ohex.encode v'));
                         None)
-                    acc
+                    csums, errs
               end
-            | _ -> acc) HM.empty csums
+            | v ->
+              csums, `Msg (Fmt.str "bad checksum data: %s" (OpamPrinter.FullPos.value v)) :: errs)
+          (HM.empty, []) csums
       in
-      Some csums
+      if HM.is_empty csums then
+        match errs with
+        | hd :: tl -> Error hd, tl
+        | [] -> Error (`Msg "empty checksums"), []
+      else
+        Ok csums, errs
     | Some { pelem = Variable (_, { pelem = String csum ; _ }) ; _ } ->
       begin match decode_digest filename csum with
-        | None -> None
-        | Some (h, v) -> Some (HM.singleton h v)
+        | Error _ as e -> e, []
+        | Ok (h, v) -> Ok (HM.singleton h v), []
       end
     | _ ->
       Log.warn (fun m -> m "couldn't decode checksum in %s" filename);
-      None
+      Error (`Msg "couldn't find or decode 'checksum'"), []
   in
-  match url, csum with
-  | Some url, Some cs -> Some (url, cs)
-  | _ -> None
+  (match url, csum with
+   | Ok url, Ok csum -> Ok (url, csum)
+   | Error _ as e, _
+   | _, (Error _ as e) -> e), csum_errs
 
 let extract_checksums_and_urls filename opam =
   let open OpamParserTypes.FullPos in
-  List.fold_left (fun acc ->
+  List.fold_left (fun (csum_urls, errs) ->
       function
       | { pelem = Section ({ section_kind = { pelem = "url" ; _ } ; section_items = { pelem = items ; _ } ; _ }) ; _} ->
         begin match extract_url_checksum filename items with
-          | None -> acc
-          | Some url -> url :: acc
+          | Error `Msg msg, errs' -> csum_urls, `Msg ("url: " ^ msg) :: errs' @ errs
+          | Ok url, errs' -> url :: csum_urls, errs' @ errs
         end
       | { pelem = Section ({ section_kind = { pelem = "extra-source" ; _ } ; section_name = Some { pelem ; _ } ;  section_items = { pelem = items ; _ };  _ }) ; _} ->
         begin
           Log.debug (fun m -> m "extracting for extra-source %s in %s" filename pelem);
           match extract_url_checksum filename items with
-          | None -> acc
-          | Some url -> url :: acc
+          | Error `Msg msg, errs' -> csum_urls, `Msg ("extra-source " ^ pelem ^ " " ^ msg) :: errs' @ errs
+          | Ok url, errs' -> url :: csum_urls, errs' @ errs
         end
-      | _ -> acc)
-    [] opam.file_contents
+      | _ -> csum_urls, errs)
+    ([], []) opam.file_contents
 
 let extract_urls filename str =
   (* in an opam file, there may be:
@@ -121,6 +135,6 @@ let extract_urls filename str =
   in
   if unavailable then
     (Log.debug (fun m -> m "%s is marked unavailable, skipping" filename);
-     [])
+     [], [])
   else
     extract_checksums_and_urls filename opamfile
diff --git a/mirage/unikernel.ml b/mirage/unikernel.ml
index 4fac591..fe86de3 100644
--- a/mirage/unikernel.ml
+++ b/mirage/unikernel.ml
@@ -101,6 +101,11 @@ module Make
         hash_to_string h ^ "=" ^ Ohex.encode v ^ "\n" ^ acc)
       hm ""
 
+  let parse_errors = ref SM.empty
+
+  let add_parse_error filename error =
+    parse_errors := SM.add filename error !parse_errors
+
   module Git = struct
     let contents store =
       let explore = ref [ Mirage_kv.Key.empty ] in
@@ -135,31 +140,32 @@ module Make
 
     let find_urls acc path data =
       if Mirage_kv.Key.basename path = "opam" then
-        (* TODO: parser errors are logged (should be reported to status page) *)
-        (try
-           let url_csums = Opam_file.extract_urls (Mirage_kv.Key.to_string path) data in
-           List.fold_left (fun acc (url, csums) ->
-               if HM.cardinal csums = 0 then
-                 (Logs.warn (fun m -> m "no checksums for %s, ignoring" url); acc)
-               else
-                 SM.update url (function
-                     | None -> Some csums
-                     | Some csums' ->
-                       if HM.for_all (fun h v ->
-                           match HM.find_opt h csums with
-                           | None -> true | Some v' -> String.equal v v')
-                           csums'
-                       then
-                         Some (HM.union (fun _h v _v' -> Some v) csums csums')
-                       else begin
-                         Logs.warn (fun m -> m "mismatching hashes for %s: %s vs %s"
-                                       url (hm_to_s csums') (hm_to_s csums));
-                         None
-                       end) acc) acc url_csums
-         with exn ->
-           Logs.warn (fun m -> m "some error in %a, ignoring %s"
-                         Mirage_kv.Key.pp path (Printexc.to_string exn));
-           acc)
+        let path = Mirage_kv.Key.to_string path in
+        let url_csums, errs = Opam_file.extract_urls path data in
+        List.iter (fun (`Msg msg) -> add_parse_error path msg) errs;
+        List.fold_left (fun acc (url, csums) ->
+            if HM.cardinal csums = 0 then
+              (Logs.warn (fun m -> m "no checksums for %s, ignoring" url);
+               add_parse_error path ("no checksums for " ^ url);
+               acc)
+            else
+              SM.update url (function
+                  | None -> Some csums
+                  | Some csums' ->
+                    if HM.for_all (fun h v ->
+                        match HM.find_opt h csums with
+                        | None -> true | Some v' -> String.equal v v')
+                        csums'
+                    then
+                      Some (HM.union (fun _h v _v' -> Some v) csums csums')
+                    else begin
+                      Logs.warn (fun m -> m "mismatching hashes for %s: %s vs %s"
+                                    url (hm_to_s csums') (hm_to_s csums));
+                      add_parse_error path (Fmt.str
+                                              "mismatching hashes for %s: %s vs %s"
+                                              url (hm_to_s csums') (hm_to_s csums));
+                      None
+                    end) acc) acc url_csums
       else
         acc
 
@@ -654,27 +660,37 @@ stamp: %S
           (SM.cardinal disk.Disk.md5s)
           (KV.free disk.Disk.dev)
       in
+      let sort_by_ts a b = Ptime.compare a b in
       let active_downloads =
         let header = "<h2>Active downloads</h2><ul>" in
         let content =
-          SM.fold (fun url (ts, bytes_written) acc ->
-              ("<li>" ^ Ptime.to_rfc3339 ?tz_offset_s:None ts ^ ": " ^ url ^ " " ^ string_of_int bytes_written ^ " bytes written to disk</li>")
-              ^ acc)
-            !active_downloads ""
+          SM.bindings !active_downloads |>
+          List.sort (fun (_, (a, _)) (_, (b, _)) -> sort_by_ts a b) |>
+          List.map (fun (url, (ts, bytes_written)) ->
+              "<li>" ^ Ptime.to_rfc3339 ?tz_offset_s:None ts ^ ": " ^ url ^ " " ^ string_of_int bytes_written ^ " bytes written to swap</li>")
         in
-        header ^ content ^ "</ul>"
+        header ^ String.concat "" content ^ "</ul>"
       and failed_downloads =
         let header = "<h2>Failed downloads</h2><ul>" in
         let content =
-          SM.fold (fun url (ts, reason) acc ->
-              ("<li>" ^ Ptime.to_rfc3339 ?tz_offset_s:None ts ^ ": " ^ url ^ " " ^ reason ^ "</li>")
-              ^ acc)
-            !failed_downloads ""
+          SM.bindings !failed_downloads |>
+          List.sort (fun (_, (a, _)) (_, (b, _)) -> sort_by_ts a b) |>
+          List.map (fun (url, (ts, reason)) ->
+              "<li>" ^ Ptime.to_rfc3339 ?tz_offset_s:None ts ^ ": " ^ url ^ " " ^ reason ^ "</li>")
         in
-        header ^ content ^ "</ul>"
+        header ^ String.concat "" content ^ "</ul>"
+      and parse_errors =
+        let header = "<h2>Parse errors</h2><ul>" in
+        let content =
+          SM.bindings !parse_errors |>
+          List.sort (fun (a, _) (b, _) -> String.compare a b) |>
+          List.map (fun (filename, reason) ->
+              "<li>" ^ filename ^ ": " ^ reason ^ "</li>")
+        in
+        header ^ String.concat "" content ^ "</ul>"
       in
       "<html><head><title>Opam-mirror status page</title></head><body><h1>Opam mirror status</h1><div>"
-      ^ String.concat "</div><div>" [ archive_stats ; active_downloads ; failed_downloads ]
+      ^ String.concat "</div><div>" [ archive_stats ; active_downloads ; failed_downloads ; parse_errors ]
         ^ "</div></body></html>"
 
     let not_modified request (modified, etag) =