diff --git a/app/api_report.go b/app/api_report.go
index 0aa046f043..54ad023523 100644
--- a/app/api_report.go
+++ b/app/api_report.go
@@ -9,6 +9,11 @@ import (
 // Raw report handler
 func makeRawReportHandler(rep Reporter) CtxHandlerFunc {
 	return func(ctx context.Context, w http.ResponseWriter, r *http.Request) {
-		respondWith(w, http.StatusOK, rep.Report(ctx))
+		report, err := rep.Report(ctx)
+		if err != nil {
+			respondWith(w, http.StatusInternalServerError, err.Error())
+			return
+		}
+		respondWith(w, http.StatusOK, report)
 	}
 }
diff --git a/app/api_topologies.go b/app/api_topologies.go
index 4d2e424e8b..6930aeaf4e 100644
--- a/app/api_topologies.go
+++ b/app/api_topologies.go
@@ -195,7 +195,12 @@ func (r *registry) walk(f func(APITopologyDesc)) {
 // makeTopologyList returns a handler that yields an APITopologyList.
 func (r *registry) makeTopologyList(rep Reporter) CtxHandlerFunc {
 	return func(ctx context.Context, w http.ResponseWriter, req *http.Request) {
-		topologies := r.renderTopologies(rep.Report(ctx), req)
+		report, err := rep.Report(ctx)
+		if err != nil {
+			respondWith(w, http.StatusInternalServerError, err.Error())
+			return
+		}
+		topologies := r.renderTopologies(report, req)
 		respondWith(w, http.StatusOK, topologies)
 	}
 }
diff --git a/app/api_topology.go b/app/api_topology.go
index 639ecfb5f7..e28df96193 100644
--- a/app/api_topology.go
+++ b/app/api_topology.go
@@ -28,8 +28,13 @@ type APINode struct {
 
 // Full topology.
 func handleTopology(ctx context.Context, rep Reporter, renderer render.Renderer, w http.ResponseWriter, r *http.Request) {
+	report, err := rep.Report(ctx)
+	if err != nil {
+		respondWith(w, http.StatusInternalServerError, err.Error())
+		return
+	}
 	respondWith(w, http.StatusOK, APITopology{
-		Nodes: renderer.Render(rep.Report(ctx)).Prune(),
+		Nodes: renderer.Render(report).Prune(),
 	})
 }
 
@@ -54,15 +59,19 @@ func handleWs(ctx context.Context, rep Reporter, renderer render.Renderer, w htt
 func handleNode(topologyID, nodeID string) func(context.Context, Reporter, render.Renderer, http.ResponseWriter, *http.Request) {
 	return func(ctx context.Context, rep Reporter, renderer render.Renderer, w http.ResponseWriter, r *http.Request) {
 		var (
-			rpt      = rep.Report(ctx)
-			rendered = renderer.Render(rep.Report(ctx))
-			node, ok = rendered[nodeID]
+			report, err = rep.Report(ctx)
+			rendered    = renderer.Render(report)
+			node, ok    = rendered[nodeID]
 		)
+		if err != nil {
+			respondWith(w, http.StatusInternalServerError, err.Error())
+			return
+		}
 		if !ok {
 			http.NotFound(w, r)
 			return
 		}
-		respondWith(w, http.StatusOK, APINode{Node: detailed.MakeNode(topologyID, rpt, rendered, node)})
+		respondWith(w, http.StatusOK, APINode{Node: detailed.MakeNode(topologyID, report, rendered, node)})
 	}
 }
 
@@ -103,7 +112,12 @@ func handleWebsocket(
 	defer rep.UnWait(ctx, wait)
 
 	for {
-		newTopo := renderer.Render(rep.Report(ctx)).Prune()
+		report, err := rep.Report(ctx)
+		if err != nil {
+			log.Errorf("Error generating report: %v", err)
+			return
+		}
+		newTopo := renderer.Render(report).Prune()
 		diff := render.TopoDiff(previousTopo, newTopo)
 		previousTopo = newTopo
 
diff --git a/app/collector.go b/app/collector.go
index 6c2f72730b..7269e1bffe 100644
--- a/app/collector.go
+++ b/app/collector.go
@@ -14,7 +14,7 @@ import (
 // Reporter is something that can produce reports on demand. It's a convenient
 // interface for parts of the app, and several experimental components.
 type Reporter interface {
-	Report(context.Context) report.Report
+	Report(context.Context) (report.Report, error)
 	WaitOn(context.Context, chan struct{})
 	UnWait(context.Context, chan struct{})
 }
@@ -22,7 +22,7 @@ type Reporter interface {
 // Adder is something that can accept reports. It's a convenient interface for
 // parts of the app, and several experimental components.
 type Adder interface {
-	Add(context.Context, report.Report)
+	Add(context.Context, report.Report) error
 }
 
 // A Collector is a Reporter and an Adder
@@ -83,7 +83,7 @@ func NewCollector(window time.Duration) Collector {
 var now = time.Now
 
 // Add adds a report to the collector's internal state. It implements Adder.
-func (c *collector) Add(_ context.Context, rpt report.Report) {
+func (c *collector) Add(_ context.Context, rpt report.Report) error {
 	c.mtx.Lock()
 	defer c.mtx.Unlock()
 	c.reports = append(c.reports, timestampReport{now(), rpt})
@@ -92,11 +92,12 @@ func (c *collector) Add(_ context.Context, rpt report.Report) {
 	if rpt.Shortcut {
 		c.Broadcast()
 	}
+	return nil
 }
 
 // Report returns a merged report over all added reports. It implements
 // Reporter.
-func (c *collector) Report(_ context.Context) report.Report {
+func (c *collector) Report(_ context.Context) (report.Report, error) {
 	c.mtx.Lock()
 	defer c.mtx.Unlock()
 
@@ -105,7 +106,7 @@ func (c *collector) Report(_ context.Context) report.Report {
 	if c.cached != nil && len(c.reports) > 0 {
 		oldest := now().Add(-c.window)
 		if c.reports[0].timestamp.Before(oldest) {
-			return *c.cached
+			return *c.cached, nil
 		}
 	}
 	c.reports = clean(c.reports, c.window)
@@ -118,7 +119,7 @@ func (c *collector) Report(_ context.Context) report.Report {
 	}
 	rpt.ID = fmt.Sprintf("%x", id.Sum64())
 	c.cached = &rpt
-	return rpt
+	return rpt, nil
 }
 
 type timestampReport struct {
diff --git a/app/collector_test.go b/app/collector_test.go
index 81caf11724..4006b05e75 100644
--- a/app/collector_test.go
+++ b/app/collector_test.go
@@ -23,12 +23,20 @@ func TestCollector(t *testing.T) {
 	r2 := report.MakeReport()
 	r2.Endpoint.AddNode("bar", report.MakeNode())
 
-	if want, have := report.MakeReport(), c.Report(ctx); !reflect.DeepEqual(want, have) {
+	have, err := c.Report(ctx)
+	if err != nil {
+		t.Error(err)
+	}
+	if want := report.MakeReport(); !reflect.DeepEqual(want, have) {
 		t.Error(test.Diff(want, have))
 	}
 
 	c.Add(ctx, r1)
-	if want, have := r1, c.Report(ctx); !reflect.DeepEqual(want, have) {
+	have, err = c.Report(ctx)
+	if err != nil {
+		t.Error(err)
+	}
+	if want := r1; !reflect.DeepEqual(want, have) {
 		t.Error(test.Diff(want, have))
 	}
 
@@ -36,7 +44,11 @@ func TestCollector(t *testing.T) {
 	merged := report.MakeReport()
 	merged = merged.Merge(r1)
 	merged = merged.Merge(r2)
-	if want, have := merged, c.Report(ctx); !reflect.DeepEqual(want, have) {
+	have, err = c.Report(ctx)
+	if err != nil {
+		t.Error(err)
+	}
+	if want := merged; !reflect.DeepEqual(want, have) {
 		t.Error(test.Diff(want, have))
 	}
 }
diff --git a/app/mock_reporter_test.go b/app/mock_reporter_test.go
index b5efe5e5b6..9903357e52 100644
--- a/app/mock_reporter_test.go
+++ b/app/mock_reporter_test.go
@@ -10,7 +10,7 @@ import (
 // StaticReport is used as a fixture in tests. It emulates an xfer.Collector.
 type StaticReport struct{}
 
-func (s StaticReport) Report(context.Context) report.Report  { return fixture.Report }
-func (s StaticReport) Add(context.Context, report.Report)    {}
-func (s StaticReport) WaitOn(context.Context, chan struct{}) {}
-func (s StaticReport) UnWait(context.Context, chan struct{}) {}
+func (s StaticReport) Report(context.Context) (report.Report, error) { return fixture.Report, nil }
+func (s StaticReport) Add(context.Context, report.Report) error      { return nil }
+func (s StaticReport) WaitOn(context.Context, chan struct{})         {}
+func (s StaticReport) UnWait(context.Context, chan struct{})         {}
diff --git a/app/pipe_router.go b/app/pipe_router.go
index 5bdfdf9c48..3db9813350 100644
--- a/app/pipe_router.go
+++ b/app/pipe_router.go
@@ -1,6 +1,7 @@
 package app
 
 import (
+	"fmt"
 	"io"
 	"sync"
 	"time"
@@ -29,9 +30,9 @@ const (
 
 // PipeRouter stores pipes and allows you to connect to either end of them.
 type PipeRouter interface {
-	Get(context.Context, string, End) (xfer.Pipe, io.ReadWriter, bool)
-	Release(context.Context, string, End)
-	Delete(context.Context, string)
+	Get(context.Context, string, End) (xfer.Pipe, io.ReadWriter, error)
+	Release(context.Context, string, End) error
+	Delete(context.Context, string) error
 	Stop()
 }
 
@@ -77,7 +78,7 @@ func NewLocalPipeRouter() PipeRouter {
 	return pipeRouter
 }
 
-func (pr *localPipeRouter) Get(_ context.Context, id string, e End) (xfer.Pipe, io.ReadWriter, bool) {
+func (pr *localPipeRouter) Get(_ context.Context, id string, e End) (xfer.Pipe, io.ReadWriter, error) {
 	pr.Lock()
 	defer pr.Unlock()
 	p, ok := pr.pipes[id]
@@ -91,43 +92,45 @@ func (pr *localPipeRouter) Get(_ context.Context, id string, e End) (xfer.Pipe,
 		pr.pipes[id] = p
 	}
 	if p.Closed() {
-		return nil, nil, false
+		return nil, nil, fmt.Errorf("Pipe %s closed", id)
 	}
 	end, endIO := p.end(e)
 	end.refCount++
-	return p, endIO, true
+	return p, endIO, nil
 }
 
-func (pr *localPipeRouter) Release(_ context.Context, id string, e End) {
+func (pr *localPipeRouter) Release(_ context.Context, id string, e End) error {
 	pr.Lock()
 	defer pr.Unlock()
 
 	p, ok := pr.pipes[id]
 	if !ok {
-		// uh oh
-		return
+		return fmt.Errorf("Pipe %s not found", id)
 	}
 
 	end, _ := p.end(e)
 	end.refCount--
 	if end.refCount > 0 {
-		return
+		return nil
 	}
 
 	if !p.Closed() {
 		end.lastUsedTime = mtime.Now()
 	}
+
+	return nil
 }
 
-func (pr *localPipeRouter) Delete(_ context.Context, id string) {
+func (pr *localPipeRouter) Delete(_ context.Context, id string) error {
 	pr.Lock()
 	defer pr.Unlock()
 	p, ok := pr.pipes[id]
 	if !ok {
-		return
+		return nil
 	}
 	p.Close()
 	p.tombstoneTime = mtime.Now()
+	return nil
 }
 
 func (pr *localPipeRouter) Stop() {
diff --git a/app/pipes.go b/app/pipes.go
index 6bb5742f66..7f98f65e8a 100644
--- a/app/pipes.go
+++ b/app/pipes.go
@@ -32,8 +32,8 @@ func RegisterPipeRoutes(router *mux.Router, pr PipeRouter) {
 func checkPipe(pr PipeRouter, end End) CtxHandlerFunc {
 	return func(ctx context.Context, w http.ResponseWriter, r *http.Request) {
 		id := mux.Vars(r)["pipeID"]
-		_, _, ok := pr.Get(ctx, id, end)
-		if !ok {
+		_, _, err := pr.Get(ctx, id, end)
+		if err != nil {
 			w.WriteHeader(http.StatusNoContent)
 			return
 		}
@@ -44,8 +44,9 @@ func checkPipe(pr PipeRouter, end End) CtxHandlerFunc {
 func handlePipeWs(pr PipeRouter, end End) CtxHandlerFunc {
 	return func(ctx context.Context, w http.ResponseWriter, r *http.Request) {
 		id := mux.Vars(r)["pipeID"]
-		pipe, endIO, ok := pr.Get(ctx, id, end)
-		if !ok {
+		pipe, endIO, err := pr.Get(ctx, id, end)
+		if err != nil {
+			log.Errorf("Error getting pipe %s: %v", id, err)
 			http.NotFound(w, r)
 			return
 		}
@@ -69,6 +70,8 @@ func deletePipe(pr PipeRouter) CtxHandlerFunc {
 	return func(ctx context.Context, w http.ResponseWriter, r *http.Request) {
 		pipeID := mux.Vars(r)["pipeID"]
 		log.Infof("Closing pipe %s", pipeID)
-		pr.Delete(ctx, pipeID)
+		if err := pr.Delete(ctx, pipeID); err != nil {
+			respondWith(w, http.StatusInternalServerError, err.Error())
+		}
 	}
 }
diff --git a/app/pipes_internal_test.go b/app/pipes_internal_test.go
index 1a6643933e..3089197555 100644
--- a/app/pipes_internal_test.go
+++ b/app/pipes_internal_test.go
@@ -33,9 +33,9 @@ func TestPipeTimeout(t *testing.T) {
 	// create a new pipe.
 	id := "foo"
 	ctx := context.Background()
-	pipe, _, ok := pr.Get(ctx, id, UIEnd)
-	if !ok {
-		t.Fatalf("not ok")
+	pipe, _, err := pr.Get(ctx, id, UIEnd)
+	if err != nil {
+		t.Fatalf("not ok: %v", err)
 	}
 
 	// move time forward such that the new pipe should timeout
diff --git a/app/router_test.go b/app/router_test.go
index cc80b522cd..563320ca47 100644
--- a/app/router_test.go
+++ b/app/router_test.go
@@ -75,7 +75,11 @@ func TestReportPostHandler(t *testing.T) {
 		}
 
 		ctx := context.Background()
-		if want, have := fixture.Report.Endpoint.Nodes, c.Report(ctx).Endpoint.Nodes; len(have) == 0 || len(want) != len(have) {
+		report, err := c.Report(ctx)
+		if err != nil {
+			t.Error(err)
+		}
+		if want, have := fixture.Report.Endpoint.Nodes, report.Endpoint.Nodes; len(have) == 0 || len(want) != len(have) {
 			t.Fatalf("Content-Type %s: %v", contentType, test.Diff(have, want))
 		}
 	}