diff --git a/app/server/lib/BootProbes.ts b/app/server/lib/BootProbes.ts
index adef4811..36c3786c 100644
--- a/app/server/lib/BootProbes.ts
+++ b/app/server/lib/BootProbes.ts
@@ -6,7 +6,7 @@ import { GristServer } from 'app/server/lib/GristServer';
 import * as express from 'express';
 import WS from 'ws';
 import fetch from 'node-fetch';
-import { DEFAULT_SESSION_SECRET } from 'app/server/lib/coreCreator';
+import { DEFAULT_SESSION_SECRET } from 'app/server/lib/ICreate';
 
 /**
  * Self-diagnostics useful when installing Grist.
diff --git a/app/server/lib/ICreate.ts b/app/server/lib/ICreate.ts
index 4b4d66ee..bf6fa69d 100644
--- a/app/server/lib/ICreate.ts
+++ b/app/server/lib/ICreate.ts
@@ -13,6 +13,9 @@ import {createSandbox, SpawnFn} from 'app/server/lib/NSandbox';
 import {SqliteVariant} from 'app/server/lib/SqliteCommon';
 import {ITelemetry} from 'app/server/lib/Telemetry';
 
+export const DEFAULT_SESSION_SECRET =
+  'Phoo2ag1jaiz6Moo2Iese2xoaphahbai3oNg7diemohlah0ohtae9iengafieS2Hae7quungoCi9iaPh';
+
 export interface ICreate {
 
   Billing(dbManager: HomeDBManager, gristConfig: GristServer): IBilling;
@@ -116,11 +119,7 @@ export function makeSimpleCreator(opts: {
       return createSandbox(opts.sandboxFlavor || 'unsandboxed', options);
     },
     sessionSecret() {
-      const secret = process.env.GRIST_SESSION_SECRET || sessionSecret;
-      if (!secret) {
-        throw new Error('need GRIST_SESSION_SECRET');
-      }
-      return secret;
+      return process.env.GRIST_SESSION_SECRET || sessionSecret || DEFAULT_SESSION_SECRET;
     },
     async configure() {
       for (const s of storage || []) {
diff --git a/app/server/lib/coreCreator.ts b/app/server/lib/coreCreator.ts
index 477c970b..2eda4e9f 100644
--- a/app/server/lib/coreCreator.ts
+++ b/app/server/lib/coreCreator.ts
@@ -3,14 +3,8 @@ import { checkMinIOBucket, checkMinIOExternalStorage,
 import { makeSimpleCreator } from 'app/server/lib/ICreate';
 import { Telemetry } from 'app/server/lib/Telemetry';
 
-export const DEFAULT_SESSION_SECRET =
-  'Phoo2ag1jaiz6Moo2Iese2xoaphahbai3oNg7diemohlah0ohtae9iengafieS2Hae7quungoCi9iaPh';
-
 export const makeCoreCreator = () => makeSimpleCreator({
   deploymentType: 'core',
-  // This can and should be overridden by GRIST_SESSION_SECRET
-  // (or generated randomly per install, like grist-omnibus does).
-  sessionSecret: DEFAULT_SESSION_SECRET,
   storage: [
     {
       name: 'minio',