Overview
If your Practice Test PDF will not open and displays an “incorrect key” or similar error message, this is usually caused by opening the file directly from the ZIP archive or using a PDF viewer that does not fully support the file format. This article explains how to resolve the issue on both macOS and Windows.
1. Unzip the File Before Opening
Practice Test PDFs must be opened after the ZIP file has been fully extracted.
Steps:
- Locate the downloaded ZIP file.
- Extract or “unwind” the ZIP file to a folder on your computer.
- Open the PDF from the extracted folder—not from inside the ZIP archive.
Opening the PDF directly from the ZIP can cause the “incorrect key” error.
2. Use a Supported PDF Reader
macOS Users
Use the built‑in Preview application:
- Right‑click the PDF file.
- Select Open With.
- Choose Preview.
Preview is the recommended viewer for macOS and avoids common compatibility issues.
Windows Users
Use Adobe Reader for best results.
Adobe Reader fully supports the encryption and formatting used in Practice Test PDFs.
Summary
If your Practice Test PDF shows an “incorrect key” error:
- Make sure you have extracted the ZIP file before opening the PDF.
- Use Preview on macOS or Adobe Reader on Windows.
Following these steps resolves the issue in nearly all cases.