diff --git a/src/SaveObject.ts b/src/SaveObject.ts
index 062dd39f6..95726cdac 100644
--- a/src/SaveObject.ts
+++ b/src/SaveObject.ts
@@ -160,6 +160,20 @@ function assertParsedSaveData(parsedSaveData: unknown): asserts parsedSaveData i
   }
 }
 
+/**
+ * We sometimes need the raw data in the loaded save object for debugging and showing useful error messages. This object
+ * contains only what we need.
+ */
+export const loadedSaveObjectMiniDump = {
+  /**
+   * If VersionSave exists, it is always a string. It has 3 formats:
+   * - x.y: Very early versions (0.1-0.17) used this format.
+   * - x.y.z: Starting from roughly 0.17, we used this format. Note that in some commits, we mistakenly used the x.y format.
+   * - x: Starting from v1, we used the version number instead of the version string.
+   */
+  VersionSave: undefined as string | undefined,
+};
+
 class BitburnerSaveObject implements BitburnerSaveObjectType {
   PlayerSave = "";
   AllServersSave = "";
@@ -426,6 +440,18 @@ async function loadGame(saveData: SaveData): Promise<boolean> {
   const jsonSaveString = await decodeSaveData(saveData);
 
   const saveObj: unknown = JSON.parse(jsonSaveString, Reviver);
+
+  // Extract VersionSave ASAP for debugging and showing useful error messages later. Some checks here are redundant (
+  // e.g., the object assertion) because we will do them again later, but that's okay.
+  if (
+    saveObj != null &&
+    typeof saveObj === "object" &&
+    "VersionSave" in saveObj &&
+    typeof saveObj.VersionSave === "string"
+  ) {
+    loadedSaveObjectMiniDump.VersionSave = saveObj.VersionSave;
+  }
+
   assertBitburnerSaveObjectType(saveObj);
 
   // "Mandatory"
diff --git a/src/ui/React/RecoveryRoot.tsx b/src/ui/React/RecoveryRoot.tsx
index a81912c65..623c36933 100644
--- a/src/ui/React/RecoveryRoot.tsx
+++ b/src/ui/React/RecoveryRoot.tsx
@@ -5,7 +5,7 @@ import { Settings } from "../../Settings/Settings";
 import { load } from "../../db";
 import { Router } from "../GameRoot";
 import { Page } from "../Router";
-import { type CrashReport, newIssueUrl, getCrashReport } from "../../utils/ErrorHelper";
+import { type CrashReport, newIssueUrl, getCrashReport, isSaveDataFromNewerVersions } from "../../utils/ErrorHelper";
 import { DeleteGameButton } from "./DeleteGameButton";
 import { SoftResetButton } from "./SoftResetButton";
 
@@ -16,6 +16,9 @@ import { InvalidSaveData, UnsupportedSaveData } from "../../utils/SaveDataUtils"
 import { downloadContentAsFile } from "../../utils/FileUtils";
 import { debounce } from "lodash";
 import { Engine } from "../../engine";
+import { JSONReviverError } from "../../utils/GenericReviver";
+import { loadedSaveObjectMiniDump } from "../../SaveObject";
+import { CONSTANTS } from "../../Constants";
 
 export let RecoveryMode = false;
 let sourceError: unknown;
@@ -108,6 +111,19 @@ export function RecoveryRoot({ softReset, crashReport, resetError }: IProps): Re
         Your save data is invalid. Please import a valid backup save file.
       </Typography>
     );
+  } else if (
+    sourceError instanceof JSONReviverError &&
+    isSaveDataFromNewerVersions(loadedSaveObjectMiniDump.VersionSave)
+  ) {
+    instructions = (
+      <Typography variant="h5" color={Settings.theme.warning}>
+        Your save data is from a newer version (Version number: {loadedSaveObjectMiniDump.VersionSave}). The current
+        version number is {CONSTANTS.VersionNumber}.
+        <br />
+        Please check if you are using the correct build. This may happen when you load the save data of the dev build
+        (Steam Beta or https://bitburner-official.github.io/bitburner-src) on the stable build.
+      </Typography>
+    );
   } else {
     instructions = (
       <Box>
diff --git a/src/utils/ErrorHelper.ts b/src/utils/ErrorHelper.ts
index 47dbe0761..b4d8ecb5c 100644
--- a/src/utils/ErrorHelper.ts
+++ b/src/utils/ErrorHelper.ts
@@ -195,3 +195,18 @@ Copy your save here if possible
     issueUrl,
   };
 }
+
+export function isSaveDataFromNewerVersions(versionSave?: string): boolean {
+  if (versionSave == null) {
+    return false;
+  }
+  // x.y and x.y.z formats are from pre-v1 versions.
+  if (versionSave.includes(".")) {
+    return false;
+  }
+  const versionNumber = Number(versionSave);
+  if (!Number.isFinite(versionNumber) || versionNumber <= CONSTANTS.VersionNumber) {
+    return false;
+  }
+  return true;
+}
diff --git a/src/utils/GenericReviver.ts b/src/utils/GenericReviver.ts
index a69e792a6..3712ed127 100644
--- a/src/utils/GenericReviver.ts
+++ b/src/utils/GenericReviver.ts
@@ -1,6 +1,15 @@
 import { constructorsForReviver, isReviverValue } from "./JSONReviver";
 import { validateObject } from "./Validator";
 
+export class JSONReviverError extends Error {
+  ctor: string;
+  constructor(message: string, ctor: string) {
+    super(message);
+    this.name = this.constructor.name;
+    this.ctor = ctor;
+  }
+}
+
 /**
  * A generic "smart reviver" function.
  * Looks for object values with a `ctor` property and a `data` property.
@@ -25,7 +34,7 @@ export function Reviver(_key: string, value: unknown): any {
         return value.data;
     }
     // Missing constructor with no special handling. Throw error.
-    throw new Error(`Could not locate constructor named ${value.ctor}. If the save data is valid, this is a bug.`);
+    throw new JSONReviverError(`Could not locate constructor named ${value.ctor}.`, value.ctor);
   }
 
   const obj = ctor.fromJSON(value);