After Effects 26.3.0 + Media Encoder 26.3.1 cannot export projects stored on SMB NAS unless Media Encoder is started first after every reboot

System Information

• Computer: Mac Studio
• Processor: Apple M2 Max
• Memory: 64 GB
• Operating System: macOS Sequoia 15.7.7
• After Effects: 26.3.0
• Adobe Media Encoder: 26.3.1

Description

Since updating to After Effects 26.3.0 and Adobe Media Encoder 26.3.1, we are experiencing a reproducible issue when exporting compositions from After Effects through Media Encoder.

Our production workflow uses an SMB network-attached storage (NAS) where all After Effects projects and assets are stored. Multiple designers work on the same projects, so moving projects to local storage is not a practical option.

This workflow has worked reliably for a long time and only started failing after updating to the current versions of After Effects and Media Encoder.

Projects stored on the internal SSD export correctly. The problem only occurs when the project is located on the SMB network share.

Steps to Reproduce

1. Restart the Mac.
2. Launch After Effects first.
3. Open an After Effects project located on an SMB NAS.
4. Send the composition to Adobe Media Encoder.
5. Start the export.

Actual Result

Media Encoder immediately fails before encoding starts.

The error shown is:

"Output could not be created. Check whether the output is write-protected or locked."

Occasionally the log also reports:

"Unable to read from source. Check whether it has been moved or deleted."

The temporary project inside the automatically created .aep_AME folder appears not to be accessible.

Expected Result

Media Encoder should export the composition normally, regardless of whether the After Effects project is stored on the internal SSD or on an SMB network share.

Reproducible Workaround

The following workaround succeeds every time:

1. Restart the Mac.
2. Launch Adobe Media Encoder first.
3. Clear the Media Cache.
4. Leave Media Encoder running.
5. Launch After Effects.
6. Open the project from the NAS.
7. Export works normally.

However, if After Effects is launched first, the export fails.

Clearing the Media Cache afterwards does not solve the problem.

The Mac must be restarted again before the workaround works.

Additional Information

• The issue began immediately after updating to After Effects 26.3.0 and Media Encoder 26.3.1.
• The same workflow functioned correctly in previous versions.
• The issue is 100% reproducible.
• Projects stored locally on the Mac do not show this problem.
• Only projects located on an SMB NAS are affected.
• Our workflow requires all project files to remain on the NAS because multiple users work on the same projects throughout the day.

We suspect this is a regression related to Dynamic Link initialization or handling of temporary .aep_AME projects when working from SMB network storage.

Thank you for investigating this issue.