Multiple reports indicate that Google Chrome is encountering difficulties saving files directly to network attached storage (NAS) drives and cloud backups. In January 2023, a bug report showed that the 32-bit Windows version of Chrome 109 was encountering a “can’t open this file” error when trying to save files with a universal naming convention (UNC) path. The error stated that the problem was that the save destination folder contained system files.
Another report confirmed the issue while trying to open a Dropbox file on the Arm64 version of Chrome 109 on macOS. Testing bug demo code revealed that the problem persisted. The Register also noticed that other browsers, such as Mozilla Firefox and Microsoft Edge, which are based on Chromium technology, were able to save files to network locations without any issues.
The root cause of the problem lies in the showOpenFilePicker() method in Google’s File System Access API. This API, introduced in 2019 as part of Project Fugu, aims to give web apps access to local files and directories. The project intends to grant web apps similar permissions as native platform apps, following Apple’s tendency to limit its Webkit-based Safari browser due to security concerns.

However, you’re not stuck with Safari. Alternative privacy-focused browsers have been accessible on Apple devices for a while. With the release of iOS 14 in September 2020, users have had the ability to set a different default browser than Safari. Therefore, Project Fugu appears to be a way for users to bypass Apple’s strict control over the apps they allow on their devices, despite pushback from the European Union.
According to The Register, Google has prioritized fixing the issue with the release of the stable version of Chrome 110 on January 31, 2023. An engineer from the company was quoted as saying that “blocking UNC paths broke a number of legitimate use cases.”