“Library not found” (Version IDs)

Running into a "Library not found" error in Google Apps Script completely halts script execution, breaking automated workflows and custom spreadsheet functions instantly. This issue occurs when the script engine tries to load an external code dependency using a specific version identifier that no longer exists, has been deleted, or was misconfigured in the project settings. Fixing this problem requires re-linking a valid, active version of the library inside the script editor or the project’s manifest file.

Fast-Fix: The 45-Second Solution

The "Library not found" error occurs when a script references an invalid or deleted library Version ID. Fix this by opening the Libraries panel in the Apps Script editor, selecting the affected library, and switching the version dropdown to a valid, active deployment number.

Quick Risk Snapshot

• Severity: High (Halts script execution and causes immediate script failure)
• Safe to Execute?: No (The code will throw an unhandled runtime exception and abort)
• Primary Cause: Reference to a deleted, missing, or archived version ID in the library setup
• Rare Cause: Manifest corruption during code migration between Google accounts

Low Risk vs. High Risk Paths

• Low Risk Path: If this happens in a standalone test script or a project bound to a single spreadsheet used only by you, the risk is minimal. You can open the editor and update the library version to “Head” or a newer stable number without affecting external systems.
• High Risk Path: If this occurs in an enterprise automation tool or a published Google Workspace Marketplace add-on, hundreds of active users will experience broken tools simultaneously. Fixing this requires an immediate redeployment and updating references across all child sheets or pushed releases.

How Apps Script Library Resolution Works

When a script executes code that utilizes an external library, the Apps Script engine relies on a digital handshake. It inspects the project’s manifest file (appsscript.json) under the library dependencies section. This section holds the unique Script ID and the chosen Version ID. Think of this like a physical assembly line where a mechanical arm is instructed to pull a component from bin number 4. If a developer deleted that specific deployment version during a cleanup, the bin is gone. The engine reaches out to fetch the source code, finds an empty space, and immediately shuts down the run with a "Library not found" error to prevent broken execution.

Probability Breakdown

• Deleted or Archived Version ID: 75%
• Missing Project View Permissions: 15% (Briefly noted; see Troubleshooting “Library access denied”
• Manual Entry Typo in Manifest File: 8%
• Google Server Propagation Lag: 2%

What Increases the Risk

The likelihood of encountering this error spikes under specific development conditions:

• Aggressive Cleanup of Deployments: Deleting old script deployments in the library project without checking if downstream scripts are still actively using those older version numbers.
• Account Migrations: Transferring ownership of the library script between different Google Workspace organizations or personal accounts, which can disrupt historical deployment records.
• Hardcoding Manifests: Manually typing version numbers directly into the appsscript.json file before that version has been formally created via the Manage deployments Menu in the source project.

Consequence Timeline

• Immediate (0 to 1 Hour): Automated time-based and edit triggers fail instantly. Error logs fill up with unhandled exceptions, and users see error banners on their screens.
• Short Term (1 to 24 Hours): Scheduled business processes fail to execute, data transfers stall, and custom user interface elements (like sidebar menus) fail to render.
• Long Term (1 Week+): Repeated trigger failures cause Google to automatically disable the project’s active triggers. Restoring operations will require manually auditing and resetting triggers across all connected sheets.

What This Is Confused With

It is important to isolate this issue from similar script errors:

• Script stopped: Deployment was archived: The deployment reference is active but marked as archived by an administrator. See “Script stopped: Deployment was archived”.
• Script not found: The entire library project has been deleted from Google Drive, rather than just an isolated version ID.

What To Do Right Now

• Open the Google Apps Script editor for the script throwing the error.
• On the left navigation sidebar, locate the Libraries list.
• Click the vertical ellipsis (three dots) next to the failing library and select Settings.
• Review the Version selector. If it shows a blank field or an error indicator, click the dropdown and choose the latest stable version number.
• Click Save to apply the fix.

Hard-Stop Triggers

Cease standard troubleshooting if you run into these conditions:

• Missing Library Entry: If the library is no longer listed in the sidebar, someone has removed the dependency entirely. You must find the original Script ID to re-add it.
• File in Trash: If navigating directly to the source library project URL returns a message saying the file is in the trash, stop troubleshooting the version; you must restore the project file from the Google Drive trash first.

What an Admin or Developer Will Check

An administrator or developer will inspect three critical points to resolve the breakdown:

1. Source Project Deployments: Open the library script itself, click Deploy > Manage deployments, and confirm that the version ID requested by the host script exists and is active.
2. The Appsscript.json Manifest: Check the raw project settings and look at the dependencies object to make sure the library identifier and version numbers match exactly without typos.
3. Project Access Controls: Ensure the library file in Google Drive is shared correctly so that end-users have at least “Viewer” access to pull the code.

Typical Effort Range

• Effort Level: Low to Moderate.
• Time to Fix: 5 to 10 minutes if you have access to both the host and library scripts. If the library was created by a deleted user account, it can take hours to locate a backup copy or rebuild the functions.

Related System Escalators

• If your library version issue is caused by an administrator archiving older active production lines, see “Script stopped: Deployment was archived”.
• To learn how to manage stable version numbers instead of relying on unstable development code, see Resolving “Head” vs. “Versioned” Deployment Mismatches.

Workspace Assessment

Check the version dropdown in your Libraries panel right now and change it to the most recent stable deployment number. Locking your production scripts to verified version IDs prevents sudden code breakage, but you must ensure those versions are preserved during development cleanup cycles. Update the reference today to restore code execution and re-enable your automated workflows immediately.