diff --git a/client.go b/client.go
index 0aff8734..1c2b9683 100644
--- a/client.go
+++ b/client.go
@@ -174,8 +174,15 @@ func (cli *Client) SyncWithContext(ctx context.Context) error {
 	// We will keep syncing until the syncing state changes. Either because
 	// Sync is called or StopSync is called.
 	syncingID := cli.incrementSyncingID()
-	nextBatch := cli.Store.LoadNextBatch(ctx, cli.UserID)
-	filterID := cli.Store.LoadFilterID(ctx, cli.UserID)
+	nextBatch, err := cli.Store.LoadNextBatch(ctx, cli.UserID)
+	if err != nil {
+		return err
+	}
+	filterID, err := cli.Store.LoadFilterID(ctx, cli.UserID)
+	if err != nil {
+		return err
+	}
+
 	if filterID == "" {
 		filterJSON := cli.Syncer.GetFilterJSON(cli.UserID)
 		resFilter, err := cli.CreateFilter(ctx, filterJSON)
@@ -183,7 +190,9 @@ func (cli *Client) SyncWithContext(ctx context.Context) error {
 			return err
 		}
 		filterID = resFilter.FilterID
-		cli.Store.SaveFilterID(ctx, cli.UserID, filterID)
+		if err := cli.Store.SaveFilterID(ctx, cli.UserID, filterID); err != nil {
+			return err
+		}
 	}
 	lastSuccessfulSync := time.Now().Add(-cli.StreamSyncMinAge - 1*time.Hour)
 	for {
diff --git a/crypto/sql_store.go b/crypto/sql_store.go
index c73a859a..64d62bc4 100644
--- a/crypto/sql_store.go
+++ b/crypto/sql_store.go
@@ -88,22 +88,27 @@ func (store *SQLCryptoStore) GetNextBatch(ctx context.Context) (string, error) {
 
 var _ mautrix.SyncStore = (*SQLCryptoStore)(nil)
 
-func (store *SQLCryptoStore) SaveFilterID(ctx context.Context, _ id.UserID, _ string) {}
-func (store *SQLCryptoStore) LoadFilterID(ctx context.Context, _ id.UserID) string    { return "" }
+func (store *SQLCryptoStore) SaveFilterID(ctx context.Context, _ id.UserID, _ string) error {
+	return nil
+}
+func (store *SQLCryptoStore) LoadFilterID(ctx context.Context, _ id.UserID) (string, error) {
+	return "", nil
+}
 
-func (store *SQLCryptoStore) SaveNextBatch(ctx context.Context, _ id.UserID, nextBatchToken string) {
+func (store *SQLCryptoStore) SaveNextBatch(ctx context.Context, _ id.UserID, nextBatchToken string) error {
 	err := store.PutNextBatch(ctx, nextBatchToken)
 	if err != nil {
-		// TODO handle error
+		return fmt.Errorf("unable to store batch: %w", err)
 	}
+	return nil
 }
 
-func (store *SQLCryptoStore) LoadNextBatch(ctx context.Context, _ id.UserID) string {
+func (store *SQLCryptoStore) LoadNextBatch(ctx context.Context, _ id.UserID) (string, error) {
 	nb, err := store.GetNextBatch(ctx)
 	if err != nil {
-		// TODO handle error
+		return "", fmt.Errorf("unable to load batch: %w", err)
 	}
-	return nb
+	return nb, nil
 }
 
 func (store *SQLCryptoStore) FindDeviceID() (deviceID id.DeviceID) {
diff --git a/syncstore.go b/syncstore.go
index 8b5b3a55..6c7fc9ee 100644
--- a/syncstore.go
+++ b/syncstore.go
@@ -3,6 +3,7 @@ package mautrix
 import (
 	"context"
 	"errors"
+	"fmt"
 
 	"maunium.net/go/mautrix/id"
 )
@@ -16,10 +17,10 @@ var _ SyncStore = (*AccountDataStore)(nil)
 // provided "MemorySyncStore" which just keeps data around in-memory which is lost on
 // restarts.
 type SyncStore interface {
-	SaveFilterID(ctx context.Context, userID id.UserID, filterID string)
-	LoadFilterID(ctx context.Context, userID id.UserID) string
-	SaveNextBatch(ctx context.Context, userID id.UserID, nextBatchToken string)
-	LoadNextBatch(ctx context.Context, userID id.UserID) string
+	SaveFilterID(ctx context.Context, userID id.UserID, filterID string) error
+	LoadFilterID(ctx context.Context, userID id.UserID) (string, error)
+	SaveNextBatch(ctx context.Context, userID id.UserID, nextBatchToken string) error
+	LoadNextBatch(ctx context.Context, userID id.UserID) (string, error)
 }
 
 // Deprecated: renamed to SyncStore
@@ -36,23 +37,25 @@ type MemorySyncStore struct {
 }
 
 // SaveFilterID to memory.
-func (s *MemorySyncStore) SaveFilterID(ctx context.Context, userID id.UserID, filterID string) {
+func (s *MemorySyncStore) SaveFilterID(ctx context.Context, userID id.UserID, filterID string) error {
 	s.Filters[userID] = filterID
+	return nil
 }
 
 // LoadFilterID from memory.
-func (s *MemorySyncStore) LoadFilterID(ctx context.Context, userID id.UserID) string {
-	return s.Filters[userID]
+func (s *MemorySyncStore) LoadFilterID(ctx context.Context, userID id.UserID) (string, error) {
+	return s.Filters[userID], nil
 }
 
 // SaveNextBatch to memory.
-func (s *MemorySyncStore) SaveNextBatch(ctx context.Context, userID id.UserID, nextBatchToken string) {
+func (s *MemorySyncStore) SaveNextBatch(ctx context.Context, userID id.UserID, nextBatchToken string) error {
 	s.NextBatch[userID] = nextBatchToken
+	return nil
 }
 
 // LoadNextBatch from memory.
-func (s *MemorySyncStore) LoadNextBatch(ctx context.Context, userID id.UserID) string {
-	return s.NextBatch[userID]
+func (s *MemorySyncStore) LoadNextBatch(ctx context.Context, userID id.UserID) (string, error) {
+	return s.NextBatch[userID], nil
 }
 
 // NewMemorySyncStore constructs a new MemorySyncStore.
@@ -76,25 +79,26 @@ type accountData struct {
 	NextBatch string `json:"next_batch"`
 }
 
-func (s *AccountDataStore) SaveFilterID(ctx context.Context, userID id.UserID, filterID string) {
+func (s *AccountDataStore) SaveFilterID(ctx context.Context, userID id.UserID, filterID string) error {
 	if userID.String() != s.client.UserID.String() {
 		panic("AccountDataStore must only be used with a single account")
 	}
 	s.FilterID = filterID
+	return nil
 }
 
-func (s *AccountDataStore) LoadFilterID(ctx context.Context, userID id.UserID) string {
+func (s *AccountDataStore) LoadFilterID(ctx context.Context, userID id.UserID) (string, error) {
 	if userID.String() != s.client.UserID.String() {
 		panic("AccountDataStore must only be used with a single account")
 	}
-	return s.FilterID
+	return s.FilterID, nil
 }
 
-func (s *AccountDataStore) SaveNextBatch(ctx context.Context, userID id.UserID, nextBatchToken string) {
+func (s *AccountDataStore) SaveNextBatch(ctx context.Context, userID id.UserID, nextBatchToken string) error {
 	if userID.String() != s.client.UserID.String() {
 		panic("AccountDataStore must only be used with a single account")
 	} else if nextBatchToken == s.nextBatch {
-		return
+		return nil
 	}
 
 	data := accountData{
@@ -103,7 +107,7 @@ func (s *AccountDataStore) SaveNextBatch(ctx context.Context, userID id.UserID,
 
 	err := s.client.SetAccountData(ctx, s.EventType, data)
 	if err != nil {
-		s.client.Log.Warn().Err(err).Msg("Failed to save next batch token to account data")
+		return fmt.Errorf("failed to save next batch token to account data: %w", err)
 	} else {
 		s.client.Log.Debug().
 			Str("old_token", s.nextBatch).
@@ -111,9 +115,10 @@ func (s *AccountDataStore) SaveNextBatch(ctx context.Context, userID id.UserID,
 			Msg("Saved next batch token")
 		s.nextBatch = nextBatchToken
 	}
+	return nil
 }
 
-func (s *AccountDataStore) LoadNextBatch(ctx context.Context, userID id.UserID) string {
+func (s *AccountDataStore) LoadNextBatch(ctx context.Context, userID id.UserID) (string, error) {
 	if userID.String() != s.client.UserID.String() {
 		panic("AccountDataStore must only be used with a single account")
 	}
@@ -124,15 +129,15 @@ func (s *AccountDataStore) LoadNextBatch(ctx context.Context, userID id.UserID)
 	if err != nil {
 		if errors.Is(err, MNotFound) {
 			s.client.Log.Debug().Msg("No next batch token found in account data")
+			return "", nil
 		} else {
-			s.client.Log.Warn().Err(err).Msg("Failed to load next batch token from account data")
+			return "", fmt.Errorf("failed to load next batch token from account data: %w", err)
 		}
-		return ""
 	}
 	s.nextBatch = data.NextBatch
 	s.client.Log.Debug().Str("next_batch", data.NextBatch).Msg("Loaded next batch token from account data")
 
-	return s.nextBatch
+	return s.nextBatch, nil
 }
 
 // NewAccountDataStore returns a new AccountDataStore, which stores