diff --git a/runtime/nongui/IBDatabase.pas b/runtime/nongui/IBDatabase.pas
index ab3ec71b..d1ca5c8d 100644
--- a/runtime/nongui/IBDatabase.pas
+++ b/runtime/nongui/IBDatabase.pas
@@ -1599,7 +1599,13 @@ constructor TIBTransaction.Create(AOwner: TComponent);
   FTimer.Interval := 0;
   FTimer.OnTimer := TimeoutTransaction;
   FDefaultAction := taCommit;
-  FTransactionList.Add(self);
+  { Guarded the way Destroy's Remove already is. A transaction can be
+    constructed after this unit has finalized - the LCL frees documents from
+    Application's async queue during Application.Destroy, and tearing a
+    data-aware control down there reaches IBX again - and the list is gone by
+    then. Unguarded, that is an access violation on the way out. }
+  if Assigned(FTransactionList) then
+    FTransactionList.Add(self);
   if (FTransactionName = '') and (CreateGUID(uuid) = 0) then
     FTransactionName := GUIDToString(uuid);
 end;
@@ -2407,10 +2413,18 @@ function TIBDataBase.GenerateDPB(FirebirdAPI: IFirebirdAPI; sl: TStrings): IDPB;
     case DPBItem.getParamType of
       isc_dpb_user_name, isc_dpb_password, isc_dpb_password_enc,
       isc_dpb_sys_user_name, isc_dpb_license, isc_dpb_encrypt_key,
-      isc_dpb_lc_messages, isc_dpb_lc_ctype, isc_dpb_page_size,
+      isc_dpb_lc_messages, isc_dpb_lc_ctype,
       isc_dpb_sql_role_name:
         DPBItem.SetAsString(ParamValue);
 
+      {isc_dpb_page_size is an integer parameter, not a string one. Writing it
+       with SetAsString stores the digits as text, which the clumplet writer
+       rejects outright once there are more than four of them - so
+       Params.Values['page_size'] := '16384' failed with "length of integer
+       exceeds 4 bytes (5)", and only the four-digit sizes appeared to work.}
+      isc_dpb_page_size:
+        DPBItem.SetAsInteger(StrToUInt(ParamValue));
+
       isc_dpb_sql_dialect:
       begin
         if (ParamValue = '') or (ParamValue[1] = '3') then
@@ -2492,8 +2506,13 @@ function TIBTransaction.GenerateTPB(FirebirdAPI: IFirebirdAPI; sl: TStrings): IT
   TIBTransaction.FTransactionList := TList.Create;
 
 Finalization
-  if assigned(TIBTransaction.FCriticalSection) then TIBTransaction.FCriticalSection.Free;
-  if assigned(TIBTransaction.FTransactionList) then TIBTransaction.FTransactionList.Free;
+  { FreeAndNil rather than Free: these are class vars that outlive the unit's
+    finalization in the sense that something can still reach them afterwards,
+    and Free leaves the reference dangling - so the Assigned tests guarding
+    them stayed true and went on reading released memory. Nil is what makes
+    those guards mean anything. }
+  if assigned(TIBTransaction.FCriticalSection) then FreeAndNil(TIBTransaction.FCriticalSection);
+  if assigned(TIBTransaction.FTransactionList) then FreeAndNil(TIBTransaction.FTransactionList);
 
 end.
 
diff --git a/runtime/nongui/IBXServices.pas b/runtime/nongui/IBXServices.pas
index 4f9b8c40..c9f7cf9e 100644
--- a/runtime/nongui/IBXServices.pas
+++ b/runtime/nongui/IBXServices.pas
@@ -341,11 +341,17 @@  TIBXBackupRestoreService = class(TIBXControlAndQueryService)
  private
    FStatisticsRequested: TBackupStatsOptions;
    FVerbose: Boolean;
+   FParallelWorkers: Integer;
  protected
    procedure SetServiceStartOptions; override;
    property Verbose : Boolean read FVerbose write FVerbose default False;
    property StatisticsRequested: TBackupStatsOptions read FStatisticsRequested write FStatisticsRequested;
  published
+   {Number of workers the server should use for the backup or restore, as
+    gbak -par does. Firebird 5 and later; an older server rejects the
+    parameter, so it is only sent when the server can take it. Zero or one
+    means the default, single-threaded behaviour.}
+   property ParallelWorkers: Integer read FParallelWorkers write FParallelWorkers default 0;
  end;
 
  TBackupOption = (IgnoreChecksums, IgnoreLimbo, MetadataOnly, NoGarbageCollection,
@@ -479,8 +485,10 @@   TIBXOnlineValidationService = class(TIBXControlAndQueryService)
     property DatabaseName;
   end;
 
+  {UpgradeODS is appended rather than inserted so that the existing values keep
+   their ordinals for anything already compiled against this unit.}
   TValidateOption = (CheckDB, IgnoreChecksum, KillShadows, MendDB,
-    SweepDB, ValidateDB, ValidateFull);
+    SweepDB, ValidateDB, ValidateFull, UpgradeODS);
   TValidateOptions = set of TValidateOption;
 
   { TIBXValidationService }
@@ -1694,6 +1702,13 @@ procedure TIBXValidationService.SetServiceStartOptions;
      if not (MendDB in Options) then
        param := param or isc_spb_rpr_validate_db;
   end;
+  {Firebird 5 and later: upgrade the on-disk structure in place, as
+   gfix -upgrade does, rather than by backup and restore. Only sent to a
+   server that knows the option, since an older one rejects it.}
+  if (UpgradeODS in Options) then
+  with ServicesConnection do
+    if ServerVersionNo[1] >= 5 then
+      param := param or isc_spb_rpr_upgrade_db;
   if param > 0 then
    SRB.Add(isc_spb_options).AsInteger := param;
 end;
@@ -1928,6 +1943,14 @@ procedure TIBXBackupRestoreService.SetServiceStartOptions;
   if Verbose then
     SRB.Add(isc_spb_verbose);
 
+  {Firebird 5 and later. isc_spb_bkp_parallel_workers and
+   isc_spb_res_parallel_workers are the same parameter code, so one property
+   serves both directions.}
+  if FParallelWorkers > 1 then
+  with ServicesConnection do
+    if ServerVersionNo[1] >= 5 then
+      SRB.Add(isc_spb_bkp_parallel_workers).AsInteger := FParallelWorkers;
+
   with ServicesConnection do
   {Firebird 2.5.5 and later}
   if (ServerVersionNo[1] < 2) or