diff --git a/lib/permissions/minimally-encoded-raw-thread-info-validators.js b/lib/permissions/minimally-encoded-raw-thread-info-validators.js
--- a/lib/permissions/minimally-encoded-raw-thread-info-validators.js
+++ b/lib/permissions/minimally-encoded-raw-thread-info-validators.js
@@ -36,6 +36,26 @@
   specialRole: t.maybe(specialRoleValidator),
 });
 
+type RoleInfoPossiblyWithIsDefaultField = {
+  ...RoleInfo,
+  isDefault?: boolean,
+};
+// This validator is to be used in `convertClientDBThreadInfoToRawThreadInfo`
+// which validates the persisted JSON blob BEFORE any migrations are run.
+// `roleInfoValidator` will fail for persisted `RoleInfo`s that include
+// the `isDefault` field. Figured it made sense to create a separate validator
+// instead of adding complexity to `roleInfoValidator` which should maintain
+// 1:1 correspondance with the `RoleInfo` type.
+const persistedRoleInfoValidator: TInterface<RoleInfoPossiblyWithIsDefaultField> =
+  tShape<RoleInfoPossiblyWithIsDefaultField>({
+    id: tID,
+    name: t.String,
+    minimallyEncoded: tBool(true),
+    permissions: t.list(tHexEncodedRolePermission),
+    specialRole: t.maybe(specialRoleValidator),
+    isDefault: t.maybe(t.Boolean),
+  });
+
 const memberInfoValidator: TInterface<MemberInfo> = tShape<MemberInfo>({
   ...legacyMemberInfoValidator.meta.props,
   minimallyEncoded: tBool(true),
@@ -58,6 +78,7 @@
 export {
   memberInfoValidator,
   roleInfoValidator,
+  persistedRoleInfoValidator,
   threadCurrentUserInfoValidator,
   rawThreadInfoValidator,
   mixedRawThreadInfoValidator,
diff --git a/lib/permissions/minimally-encoded-thread-permissions.test.js b/lib/permissions/minimally-encoded-thread-permissions.test.js
--- a/lib/permissions/minimally-encoded-thread-permissions.test.js
+++ b/lib/permissions/minimally-encoded-thread-permissions.test.js
@@ -2,6 +2,7 @@
 
 import {
   memberInfoValidator,
+  persistedRoleInfoValidator,
   rawThreadInfoValidator,
   roleInfoValidator,
   threadCurrentUserInfoValidator,
@@ -404,6 +405,21 @@
   });
 });
 
+describe('persistedRoleInfoValidator', () => {
+  it('should validate persisted RoleInfo with isDefault field', () => {
+    expect(
+      persistedRoleInfoValidator.is({
+        minimallyEncoded: true,
+        id: 'roleID',
+        name: 'roleName',
+        permissions: ['abc', 'def'],
+        specialRole: specialRoles.DEFAULT_ROLE,
+        isDefault: true,
+      }),
+    ).toBe(true);
+  });
+});
+
 describe('minimallyEncodedThreadCurrentUserInfoValidator', () => {
   it('should validate correctly formed MinimallyEncodedThreadCurrentUserInfo', () => {
     expect(
diff --git a/lib/utils/thread-ops-utils.js b/lib/utils/thread-ops-utils.js
--- a/lib/utils/thread-ops-utils.js
+++ b/lib/utils/thread-ops-utils.js
@@ -4,7 +4,7 @@
 
 import {
   memberInfoValidator,
-  roleInfoValidator,
+  persistedRoleInfoValidator,
   threadCurrentUserInfoValidator,
 } from '../permissions/minimally-encoded-raw-thread-info-validators.js';
 import type {
@@ -66,7 +66,7 @@
   ).reduce((acc: { [string]: RoleInfo }, roleID: string) => {
     const roleInfo = rawRoles[roleID];
     invariant(
-      roleInfoValidator.is(roleInfo) ||
+      persistedRoleInfoValidator.is(roleInfo) ||
         clientLegacyRoleInfoValidator.is(roleInfo),
       'rawRole must be valid [MinimallyEncoded/Legacy]RoleInfo',
     );