Batch destination overwrite behavior and missing name-collision constraint

Overwrite Behavior in Photoshop Batch

Photoshop does not provide a native option to skip existing files or automatically rename files upon collision during a File > Automate > Batch process. If a destination file already exists with the same name as the output, Photoshop will silently overwrite it without prompting the user. This behavior is not configurable via Preferences or the Batch dialog.

OS Delegation and Permission Boundaries

Overwrite handling is delegated entirely to the host operating system's file-system APIs. Photoshop requests a write operation, and the OS determines the outcome based on current permissions:

• Local Writable Folders: The OS permits the write, resulting in a silent replacement of the existing file.
• Read-Only Folders: The OS returns an access-denied error. Photoshop surfaces this as a generic "Could not save" warning but continues processing the remaining files in the batch.
• Network Destinations: Behavior is identical to local folders, governed by the SMB/NFS share permissions. If the user has write access, the file is overwritten; if not, an OS-level error is triggered.

Verification and Risk Mitigation

Because silent overwrites can lead to permanent data loss in production environments, the following verification and safety steps are recommended:

Verification Steps

1. Collision Test: Save a test file to a folder, then run a Batch process with the same naming template to the same folder. Confirm the original file is replaced without a prompt.
2. Permission Test: Set a destination folder to read-only at the OS level and run the Batch. Confirm that Photoshop reports a save error but does not halt the entire queue.

Safe Workflow Recommendations

• Unique Destination Folders: Instead of relying on naming templates, set the Destination > Folder to a new, timestamped directory for every run.
• Pre-run Validation: Use a script (ExtendScript or UXP) to scan the destination folder for existing filenames before triggering the Batch process.
• Permission Auditing: Verify write access via the OS before starting large batches on network shares. On Windows, use icacls "C:\path\to\folder"; on macOS, use ls -lO "/path/to/folder".

Diagnostic Detail

Are you utilizing a custom Action that includes a specific "Save As" step with a hardcoded filename? If so, the Batch dialog's naming options may be ignored, increasing the risk of silent overwrites.