The release of iOS 13.5 and iPadOS 13.5 marked a pivotal moment in Apple’s software history, serving as a critical bridge between traditional feature updates and emergency public health infrastructure. Released in May 2020, this software iteration was not merely a routine maintenance patch; it was engineered to address two urgent realities of the global pandemic: the need for digital contact tracing and the physical impediment face masks posed to biometric security. While the update is no longer the latest version available for modern devices, understanding its architecture, installation methods, and specific device compatibility remains relevant for users maintaining older hardware or performing archival restores. This article details the technical specifications, installation procedures, and device support matrix for the iOS 13.5 and iPadOS 13.5 updates.
Core Features and Public Health Integration
The primary objective of the iOS 13.5 and iPadOS 13.5 updates was the integration of the Apple-Google COVID-19 Exposure Notification API. This framework allowed public health authorities to deploy contact tracing applications that utilized Bluetooth technology to identify close contacts with confirmed cases, without compromising user location data or privacy. This addition represented a significant shift in how mobile operating systems interacted with global health initiatives, embedding government-grade health tools directly into the core operating system.
Simultaneously, the update addressed a critical usability issue introduced by widespread mask mandates. Prior to iOS 13.5, Face ID failed when a user’s nose and mouth were obscured, forcing users to repeatedly enter their passcode. iOS 13.5 introduced a detection mechanism that recognizes when a face mask is being worn. Upon detection, the system bypasses the Face ID attempt and immediately presents the passcode field, allowing for a swift swipe-up and entry sequence. This optimization reduced friction in high-traffic environments such as grocery stores, where users often juggle bags and require quick device access while adhering to social distancing protocols.
Beyond these headline features, the update included essential security patches. As a "pandemic" update, it also served as a vehicle for critical system stability and security fixes, ensuring that devices remained secure against emerging vulnerabilities during a period of increased remote work and online activity.
Installation Methods and System Requirements
Users have two primary methods for installing iOS 13.5 or iPadOS 13.5: Over-the-Air (OTA) updates and local restore via IPSW files. The method chosen depends on the user’s need for a clean install versus a standard incremental update, as well as the hardware capabilities of the device.
Over-the-Air (OTA) Updates
For most users, the OTA method is the standard approach. This process requires an active Wi-Fi connection and a sufficient battery level to prevent interruption during the installation process. The steps to perform an OTA update are as follows:
- Connect the device to a Wi-Fi network to ensure stable download speeds and prevent cellular data usage.
- Ensure the device has at least 50% battery remaining. If the battery is lower, connect the device to a power source.
- Launch the Settings application.
- Navigate to the General section, then select Software Update.
- Once the iOS 13.5 or iPadOS 13.5 update is detected, tap the Download and Install button.
The size of the update varies significantly depending on the specific device model and its storage architecture. While smaller devices may download a lightweight delta update, larger devices with more complex system partitions may require a full firmware download, which can range from 3.3 GiB to nearly 5 GiB.
Local Restore via IPSW Files
For users requiring a clean install, troubleshooting persistent software issues, or those without reliable Wi-Fi, downloading the IPSW (iOS/iPadOS/iPhone Software Update) file directly is the preferred method. This approach requires a computer running macOS or Windows with iTunes or Finder support. The IPSW files for iOS 13.5 are identified by build number 17F75 for most iPhone and iPad models, while specific Apple TV models may use build 17L562.
To perform a local restore:
- Download the specific IPSW file corresponding to the device model from a trusted source.
- Connect the device to the computer via a USB cable.
- Open Finder (on macOS Catalina or later) or iTunes (on Windows or older macOS).
- Put the device into recovery mode by following the specific button sequence for that hardware model.
- Select the option to Restore, then locate and select the downloaded IPSW file.
This method ensures a fresh installation of the operating system, removing all previous data and settings, which can resolve deep-seated software conflicts.
Device Compatibility and Support Matrix
Not all Apple devices are capable of running iOS 13.5 or iPadOS 13.5. The update supports a wide range of hardware released from 2015 through 2020. It is critical to identify the specific device model, as hardware variations (such as Wi-Fi versus Cellular models) often require distinct IPSW files.
The following table details the compatible iPhone models for iOS 13.5, including their respective file sizes and build numbers. Note that these figures represent the full restore IPSW files released on May 20, 2020.
| Device Model | Build Number | File Size | IPSW Filename |
|---|---|---|---|
| iPhone 11 Pro Max | 17F75 | 4.9 GiB | iPhone11,2,iPhone11,4,iPhone11,6,iPhone12,3,iPhone12,513.517F75_Restore.ipsw |
| iPhone 11 Pro | 17F75 | 4.9 GiB | iPhone11,2,iPhone11,4,iPhone11,6,iPhone12,3,iPhone12,513.517F75_Restore.ipsw |
| iPhone XS Max | 17F75 | 4.9 GiB | iPhone11,2,iPhone11,4,iPhone11,6,iPhone12,3,iPhone12,513.517F75_Restore.ipsw |
| iPhone 11 | 17F75 | 4.4 GiB | iPhone11,8,iPhone12,113.517F75_Restore.ipsw |
| iPhone XR | 17F75 | 4.4 GiB | iPhone11,8,iPhone12,113.517F75_Restore.ipsw |
| iPhone 7 Plus | 17F75 | 4.0 GiB | iPhone5.5P313.517F75_Restore.ipsw |
| iPhone XS | 17F75 | N/A | Part of Pro/Max IPSW bundle |
| iPhone 8 Plus | 17F75 | N/A | Shared IPSW with iPhone 8/XS Max architecture |
| iPhone 7 | 17F75 | 3.8 GiB | iPhone4.7P313.517F75_Restore.ipsw |
| iPhone 8 | 17F75 | N/A | Shared IPSW with iPhone 7/XR architecture |
| iPhone SE (2020) | 17F75 | 3.9 GiB | iPhone12,813.517F75_Restore.ipsw |
| iPhone SE | 17F75 | 3.5 GiB | iPhone4.064bit13.517F75_Restore.ipsw |
| iPhone 6s Plus | 17F75 | 3.7 GiB | iPhone5.513.517F75Restore.ipsw |
| iPhone 6s | 17F75 | 3.5 GiB | iPhone4.713.517F75Restore.ipsw |
| iPhone X | 17F75 | N/A | Shared IPSW with iPhone 7/XR architecture |
| iPhone XR (China) | 17F75 | 4.9 GiB | Specific regional variant |
For iPad users, the iPadOS 13.5 update supported a broad array of devices, ranging from the original iPad Air to the newer iPad Pro models. The compatibility list includes:
- iPad Pro 12.9-inch (1st, 2nd, 3rd, and 4th generations)
- iPad Pro 11-inch (2018 and 2020 models)
- iPad Pro 10.5-inch
- iPad Pro 9.7-inch
- iPad 7 (10.2-inch, 2019 model)
- iPad 6 (9.7-inch, 2018 model)
- iPad 5 (9.7-inch, 2017 model)
- iPad Air 3 (2019 model)
- iPad Air 2
- iPad mini 5 (2019 model)
- iPad mini 4
Specific IPSW files for these iPads vary by model identifier (e.g., iPad5,1 for iPad mini 4 Wi-Fi, iPad8,1 for iPad Pro 11-inch 2018 Wi-Fi). Users must match their device’s hardware identifier to the correct IPSW file to ensure a successful restore. Additionally, the Apple TV 4 (AppleTV5,3) received an update to tvOS 13.5 (Build 17L562), extending the exposure notification and security patches to the living room ecosystem.
Technical Considerations and Legacy Support
It is important to note that while iOS 13.5 was a significant update in 2020, Apple has since released numerous subsequent versions, including iOS 14, 15, 16, and later iterations. Most devices that were capable of running iOS 13.5 are now eligible for much newer software versions. However, there are scenarios where accessing iOS 13.5 remains necessary. For instance, users with older devices that reached their final supported iOS version at 13.5 (such as the iPad Air 2 or iPad mini 4) may need to restore to this version if they are performing a clean install and cannot update further.
Furthermore, the Exposure Notification API introduced in 13.5 laid the groundwork for future privacy-focused health features in iOS. The technical architecture of this update, particularly the way it handled Bluetooth signaling for contact tracing without user location data, became a standard for subsequent versions. Understanding the IPSW structure of 13.5 is therefore valuable for archivists, jailbreak communities, and users maintaining specific legacy workflows.
Conclusion
The iOS 13.5 and iPadOS 13.5 updates represent a unique intersection of software engineering and public health necessity. By introducing the Apple-Google Exposure Notification API and optimizing Face ID for mask-wearing users, Apple addressed immediate societal challenges with technical precision. The availability of direct IPSW downloads ensures that users can perform clean installs or restore devices to this specific milestone version when required. While newer updates have since superseded 13.5 in feature sets and security patches, the 13.5 update remains a critical historical marker in mobile operating system development, demonstrating the adaptability of platform software in crisis scenarios. Users maintaining older hardware or seeking to replicate specific software environments should utilize the provided IPSW filenames and build numbers to ensure compatibility and integrity during the restore process.