diff --git a/federationapi/routing/send.go b/federationapi/routing/send.go
index 191e13ef7..079e121f9 100644
--- a/federationapi/routing/send.go
+++ b/federationapi/routing/send.go
@@ -211,7 +211,24 @@ func (t *txnReq) processEventWithMissingState(e gomatrixserverlib.Event) error {
 		return err
 	}
 	// Check that the event is allowed by the state.
+retryAllowedState:
 	if err := checkAllowedByState(e, state.StateEvents); err != nil {
+		switch missing := err.(type) {
+		case gomatrixserverlib.MissingAuthEventError:
+			// An auth event was missing so let's look up that event over federation
+			for _, s := range state.StateEvents {
+				if s.EventID() != missing.AuthEventID {
+					continue
+				}
+				err = t.processEventWithMissingState(s)
+				// If there was no error retrieving the event from federation then
+				// we assume that it succeeded, so retry the original state check
+				if err == nil {
+					goto retryAllowedState
+				}
+			}
+		default:
+		}
 		return err
 	}
 	// pass the event along with the state to the roomserver
diff --git a/go.mod b/go.mod
index e3d75c6e6..924c4b67d 100644
--- a/go.mod
+++ b/go.mod
@@ -8,7 +8,7 @@ require (
 	github.com/matrix-org/go-http-js-libp2p v0.0.0-20200304160008-4ec1129a00c4
 	github.com/matrix-org/go-sqlite3-js v0.0.0-20200304164012-aa524245b658
 	github.com/matrix-org/gomatrix v0.0.0-20190528120928-7df988a63f26
-	github.com/matrix-org/gomatrixserverlib v0.0.0-20200306130050-41bec703d851
+	github.com/matrix-org/gomatrixserverlib v0.0.0-20200306154041-df6bb9a3e424
 	github.com/matrix-org/naffka v0.0.0-20200127221512-0716baaabaf1
 	github.com/matrix-org/util v0.0.0-20190711121626-527ce5ddefc7
 	github.com/mattn/go-sqlite3 v2.0.2+incompatible
diff --git a/go.sum b/go.sum
index 50d840927..a62af5c9a 100644
--- a/go.sum
+++ b/go.sum
@@ -80,8 +80,8 @@ github.com/matrix-org/gomatrix v0.0.0-20190130130140-385f072fe9af/go.mod h1:3fxX
 github.com/matrix-org/gomatrix v0.0.0-20190528120928-7df988a63f26 h1:Hr3zjRsq2bhrnp3Ky1qgx/fzCtCALOoGYylh2tpS9K4=
 github.com/matrix-org/gomatrix v0.0.0-20190528120928-7df988a63f26/go.mod h1:3fxX6gUjWyI/2Bt7J1OLhpCzOfO/bB3AiX0cJtEKud0=
 github.com/matrix-org/gomatrixserverlib v0.0.0-20200124100636-0c2ec91d1df5/go.mod h1:FsKa2pWE/bpQql9H7U4boOPXFoJX/QcqaZZ6ijLkaZI=
-github.com/matrix-org/gomatrixserverlib v0.0.0-20200306130050-41bec703d851 h1:cUzTDgLezuL4HKKspoG6W0eq3QiEJRDX6pXsSt28/VE=
-github.com/matrix-org/gomatrixserverlib v0.0.0-20200306130050-41bec703d851/go.mod h1:FsKa2pWE/bpQql9H7U4boOPXFoJX/QcqaZZ6ijLkaZI=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20200306154041-df6bb9a3e424 h1:H61lT6ckUFIDl9qb636qNomfo0B52lFt73ecioiqF10=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20200306154041-df6bb9a3e424/go.mod h1:FsKa2pWE/bpQql9H7U4boOPXFoJX/QcqaZZ6ijLkaZI=
 github.com/matrix-org/naffka v0.0.0-20200127221512-0716baaabaf1 h1:osLoFdOy+ChQqVUn2PeTDETFftVkl4w9t/OW18g3lnk=
 github.com/matrix-org/naffka v0.0.0-20200127221512-0716baaabaf1/go.mod h1:cXoYQIENbdWIQHt1SyCo6Bl3C3raHwJ0wgVrXHSqf+A=
 github.com/matrix-org/util v0.0.0-20171127121716-2e2df66af2f5 h1:W7l5CP4V7wPyPb4tYE11dbmeAOwtFQBTW0rf4OonOS8=
diff --git a/roomserver/storage/sqlite3/events_table.go b/roomserver/storage/sqlite3/events_table.go
index d2e14309b..d01034c80 100644
--- a/roomserver/storage/sqlite3/events_table.go
+++ b/roomserver/storage/sqlite3/events_table.go
@@ -119,7 +119,6 @@ type eventStatements struct {
 	bulkSelectEventReferenceStmt           *sql.Stmt
 	bulkSelectEventIDStmt                  *sql.Stmt
 	bulkSelectEventNIDStmt                 *sql.Stmt
-	selectMaxEventDepthStmt                *sql.Stmt
 }
 
 func (s *eventStatements) prepare(db *sql.DB) (err error) {
@@ -145,7 +144,6 @@ func (s *eventStatements) prepare(db *sql.DB) (err error) {
 		{&s.bulkSelectEventReferenceStmt, bulkSelectEventReferenceSQL},
 		{&s.bulkSelectEventIDStmt, bulkSelectEventIDSQL},
 		{&s.bulkSelectEventNIDStmt, bulkSelectEventNIDSQL},
-		{&s.selectMaxEventDepthStmt, selectMaxEventDepthSQL},
 	}.prepare(db)
 }
 
@@ -488,8 +486,12 @@ func (s *eventStatements) bulkSelectEventNID(ctx context.Context, txn *sql.Tx, e
 
 func (s *eventStatements) selectMaxEventDepth(ctx context.Context, txn *sql.Tx, eventNIDs []types.EventNID) (int64, error) {
 	var result int64
-	selectStmt := common.TxStmt(txn, s.selectMaxEventDepthStmt)
-	err := selectStmt.QueryRowContext(ctx, eventNIDsAsArray(eventNIDs)).Scan(&result)
+	iEventIDs := make([]interface{}, len(eventNIDs))
+	for i, v := range eventNIDs {
+		iEventIDs[i] = v
+	}
+	sqlStr := strings.Replace(selectMaxEventDepthSQL, "($1)", common.QueryVariadic(len(iEventIDs)), 1)
+	err := txn.QueryRowContext(ctx, sqlStr, iEventIDs...).Scan(&result)
 	if err != nil {
 		return 0, err
 	}
diff --git a/syncapi/routing/messages.go b/syncapi/routing/messages.go
index 7bbe16f3c..83bf75b2e 100644
--- a/syncapi/routing/messages.go
+++ b/syncapi/routing/messages.go
@@ -16,6 +16,7 @@ package routing
 
 import (
 	"context"
+	"fmt"
 	"net/http"
 	"sort"
 	"strconv"
@@ -176,6 +177,7 @@ func (r *messagesReq) retrieveEvents() (
 		r.ctx, r.from, r.to, r.roomID, r.limit, r.backwardOrdering,
 	)
 	if err != nil {
+		err = fmt.Errorf("GetEventsInRange: %s", err)
 		return
 	}
 
@@ -226,12 +228,14 @@ func (r *messagesReq) retrieveEvents() (
 		r.ctx, events[0].EventID(),
 	)
 	if err != nil {
+		err = fmt.Errorf("EventPositionInTopology: for start event %s: %s", events[0].EventID(), err)
 		return
 	}
 	endPos, err := r.db.EventPositionInTopology(
 		r.ctx, events[len(events)-1].EventID(),
 	)
 	if err != nil {
+		err = fmt.Errorf("EventPositionInTopology: for end event %s: %s", events[len(events)-1].EventID(), err)
 		return
 	}
 	// Generate pagination tokens to send to the client using the positions