User profile for user: MaximeBichon
MaximeBichon Author
User level: Level 1
4 points

Critical SMB issue with Final Cut Pro 12.4 on macOS 27.2

External media becomes unreadable when library is stored on NAS

Description:

I am experiencing a serious issue with Final Cut Pro 12.4 on macOS 27.2 running on a Mac Studio M1 Ultra.

My professional workflow requires storing Final Cut Pro libraries directly on a NAS server using SMB.

Since updating from macOS 27.0.1 to macOS 27.2, external media linked to a Final Cut Pro library stored on the NAS can no longer be played reliably. Media may reconnect successfully but playback fails, and clips eventually become offline.

Test results:

  1. Mac Studio M1 Ultra – macOS 27.2 – Final Cut Pro 12.4:
    • Library stored on NAS + external media on NAS: DOES NOT WORK.
    • Library stored on NAS + media copied inside the library: WORKS.
    • Library stored locally on SSD + external media on NAS: WORKS and remains stable.
  1. Mac M5 Max – macOS 27.0.1 – Final Cut Pro 12.4:
    • Same NAS, same SMB shares and same external media: WORKS correctly.
  1. Additional tests:
    • QuickTime can play the original media files directly from the NAS.
    • Creating and reading symbolic links on the NAS works.
    • Creating a new Final Cut Pro library does not resolve the problem.

Expected result:

Final Cut Pro should reliably play external media stored on an SMB NAS when the library itself is also stored on that NAS.

Actual result:

External media becomes unreadable or offline when the library is stored on the NAS under macOS 27.2.

Impact:

This is a critical issue for my professional editing workflow. I need to share and access Final Cut Pro libraries directly from the NAS across multiple Macs.

The same workflow works correctly under macOS 27.0.1.

Please investigate a possible SMB-related regression introduced in macOS 27.2 affecting Final Cut Pro library access and external media playback.

Thank you.

Mac Studio (2023)

Posted on Oct 30, 2026 2:22 AM

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User profile for user: joema
joema
User level: Level 4
1,729 points

Posted on Nov 1, 2026 5:56 AM

I don't work for or represent Apple. The following is not a policy statement; it's just an informed opinion. I worked for 10 years developing SQL Server and debugging it at the source code level.


The support status of FCP libraries on NAS is somewhat unclear. For years, I have tried to warn people against doing that. The FCP library is composed of multiple SQLite relational databases undergoing almost constant writes. Those databases are exquisitely sensitive to transactional errors if the I/O system fails to work perfectly or fails to adhere to the behavioral "contract" expected by the application data management layer.


But there is an official Apple article that implies it is supported -- if you adhere to specific requirements.


"Use shared storage with Final Cut Pro"

Use shared storage with Final Cut Pro - Apple Support


- Samba 4.3.4 or later configured with modules for Apple compatibility

- vfs objects = catia fruit streams_xattr


That implies SMB1, SMB2, SMB3 or SMB4 are not sufficient since those are not a backward-compatible superset of Samba 4.3.4 and later. So I question how many people have adhered to these requirements.


Even if so, there are also questions about exactly what "supported" means in this context. Technically, it means this can be done; i.e., it is conceptually possible. But "supported" does not imply Apple will assign a senior development engineer or network engineer, configure NAS test servers for each make and model, write extensive NAS usage documentation, and continuously liaise with each NAS vendor.


Years ago when the Lumaforge Jellyfish NAS was first sold, that company had high-level expert engineering support. The device was expensive, but it was extensively tested with FCP and experts tuned it to work reliably. That is in the past, and that level of support has never been available for typical consumer NAS products.


You are your own escalation resource in these cases. When something goes wrong, FCP customers must understand that this typically requires engineering-level expertise on multiple levels: FCP, macOS, network, the specific NAS, etc. Troubleshooting can require synchronized data gathering on both client and server, and source-level interpretation of that. No retail product support organization can do that.


A more recent article, "Format storage devices for Final Cut Pro, Motion, and Compressor," says only APFS is supported (which by definition excludes NAS).

Format storage devices for Final Cut Pro, Motion, and Compressor - Apple Support


Shared NAS-based project libraries can be reliably done by Resolve because that uses a true client/server relational database (PostgreSQL), not a local database file pushed over to a NAS. FCP would need to be fundamentally rewritten to work this way.


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User profile for user: joema
joema
User level: Level 4
1,729 points

Nov 1, 2026 5:56 AM in response to MaximeBichon

I don't work for or represent Apple. The following is not a policy statement; it's just an informed opinion. I worked for 10 years developing SQL Server and debugging it at the source code level.


The support status of FCP libraries on NAS is somewhat unclear. For years, I have tried to warn people against doing that. The FCP library is composed of multiple SQLite relational databases undergoing almost constant writes. Those databases are exquisitely sensitive to transactional errors if the I/O system fails to work perfectly or fails to adhere to the behavioral "contract" expected by the application data management layer.


But there is an official Apple article that implies it is supported -- if you adhere to specific requirements.


"Use shared storage with Final Cut Pro"

Use shared storage with Final Cut Pro - Apple Support


- Samba 4.3.4 or later configured with modules for Apple compatibility

- vfs objects = catia fruit streams_xattr


That implies SMB1, SMB2, SMB3 or SMB4 are not sufficient since those are not a backward-compatible superset of Samba 4.3.4 and later. So I question how many people have adhered to these requirements.


Even if so, there are also questions about exactly what "supported" means in this context. Technically, it means this can be done; i.e., it is conceptually possible. But "supported" does not imply Apple will assign a senior development engineer or network engineer, configure NAS test servers for each make and model, write extensive NAS usage documentation, and continuously liaise with each NAS vendor.


Years ago when the Lumaforge Jellyfish NAS was first sold, that company had high-level expert engineering support. The device was expensive, but it was extensively tested with FCP and experts tuned it to work reliably. That is in the past, and that level of support has never been available for typical consumer NAS products.


You are your own escalation resource in these cases. When something goes wrong, FCP customers must understand that this typically requires engineering-level expertise on multiple levels: FCP, macOS, network, the specific NAS, etc. Troubleshooting can require synchronized data gathering on both client and server, and source-level interpretation of that. No retail product support organization can do that.


A more recent article, "Format storage devices for Final Cut Pro, Motion, and Compressor," says only APFS is supported (which by definition excludes NAS).

Format storage devices for Final Cut Pro, Motion, and Compressor - Apple Support


Shared NAS-based project libraries can be reliably done by Resolve because that uses a true client/server relational database (PostgreSQL), not a local database file pushed over to a NAS. FCP would need to be fundamentally rewritten to work this way.


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Critical SMB issue with Final Cut Pro 12.4 on macOS 27.2

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