diff --git a/obuilder b/obuilder
index d21e5bf2..bc6eca86 160000
--- a/obuilder
+++ b/obuilder
@@ -1 +1 @@
-Subproject commit d21e5bf2e05762e02e3f34b82365c514634e02ad
+Subproject commit bc6eca86e5624b32ca58fb0b5e43e7e15f188f58
diff --git a/ocurrent-plugin/connection.ml b/ocurrent-plugin/connection.ml
index 9a23d327..cbdf136b 100644
--- a/ocurrent-plugin/connection.ml
+++ b/ocurrent-plugin/connection.ml
@@ -126,9 +126,8 @@ let submit ~job ~pool ~action ~cache_hint ?src ?secrets ~urgent t ~priority ~swi
             | Lwt.Canceled as ex ->
               if !stage = `Rate_limit then Prometheus.Gauge.dec_one Metrics.queue_rate_limit
               else Log.warn (fun f -> f "Cancelled at unexpected point!");
-              Lwt.fail ex
-            | ex ->
-              Lwt.fail ex
+              Lwt.reraise ex
+            | ex -> Lwt.reraise ex
           )
       in
       limiter_thread := Some use_thread;
@@ -139,7 +138,7 @@ let submit ~job ~pool ~action ~cache_hint ?src ?secrets ~urgent t ~priority ~swi
         Lwt.pause () >>= fun () ->
         if Capability.problem sched = None then (
           (* The job failed but we're still connected to the scheduler. Report the error. *)
-          Lwt.fail_with (Fmt.str "%a" Capnp_rpc.Exception.pp err)
+          Fmt.failwith "%a" Capnp_rpc.Exception.pp err
         ) else (
           limiter_thread := None;
           begin match !stage with
diff --git a/test/test_plugin.ml b/test/test_plugin.ml
index 94ef4fc0..80764630 100644
--- a/test/test_plugin.ml
+++ b/test/test_plugin.ml
@@ -200,7 +200,7 @@ let cancel_rate_limit () =
     (fun _ -> failwith "Should have failed!")
     (function
       | Lwt.Canceled -> Lwt.return_unit
-      | ex -> Lwt.fail ex)
+      | ex -> Lwt.reraise ex)
   >>= fun () ->
   (* Finish connecting to the scheduler. *)
   let sched =
@@ -221,7 +221,7 @@ let cancel_rate_limit () =
     (fun _ -> failwith "Should have failed!")
     (function
       | Lwt.Canceled -> Lwt.return_unit
-      | ex -> Lwt.fail ex)
+      | ex -> Lwt.reraise ex)
   >>= fun () ->
   Lwt.return_unit
 
diff --git a/worker/cluster_worker.ml b/worker/cluster_worker.ml
index 0e1df94f..1b71e774 100644
--- a/worker/cluster_worker.ml
+++ b/worker/cluster_worker.ml
@@ -553,7 +553,7 @@ let run ?switch ?build ?(allow_push=[]) ?(healthcheck_period = 600.0) ?prune_thr
               | _, Some switch when not (Lwt_switch.is_on switch) -> Lwt.return `Cancelled
               | Some problem, _ ->
                 Log.info (fun f -> f "Worker loop failed (probably because queue connection failed): %a" Fmt.exn ex);
-                Lwt.fail (Failure (Fmt.to_to_string Capnp_rpc.Exception.pp problem))    (* Will retry *)
+                Fmt.failwith "%a" Capnp_rpc.Exception.pp problem    (* Will retry *)
               | None, _ ->
                 Lwt.return (`Crash ex)
            )
@@ -566,6 +566,6 @@ let run ?switch ?build ?(allow_push=[]) ?(healthcheck_period = 600.0) ?prune_thr
   in
   reconnect () >>= function
   | `Cancelled -> Lwt.return_unit
-  | `Crash ex -> Lwt.fail ex
+  | `Crash ex -> Lwt.reraise ex
 
 module Obuilder_config = Obuilder_build.Config
diff --git a/worker/context.ml b/worker/context.ml
index 73c9fd40..76bdac4b 100644
--- a/worker/context.ml
+++ b/worker/context.ml
@@ -97,7 +97,7 @@ let win32_unlink fn =
   Lwt.catch
     (fun () -> Lwt_unix.unlink fn)
     (function
-     | Unix.Unix_error (Unix.EACCES, _, _) as exn ->
+     | Unix.Unix_error (Unix.EACCES, _, _) as ex ->
         (* Try removing the read-only attribute before retrying unlink. We catch
           any exception here and ignore it in favour of the original [exn]. *)
         Lwt.catch
@@ -110,10 +110,10 @@ let win32_unlink fn =
                  (* If everything succeeded but the final removal still failed,
                    restore original permissions *)
                  Lwt_unix.chmod fn st_perm >>= fun () ->
-                 Lwt.fail exn)
+                 Lwt.reraise ex)
           )
-          (fun _ -> Lwt.fail exn)
-     | exn -> Lwt.fail exn)
+          (fun _ -> Lwt.reraise ex)
+     | ex -> Lwt.reraise ex)
 
 let unlink =
   if Sys.win32 then