Stop fighting filename too long errors when copying files to your Synology NAS encrypted shared folder. SynoTrimmer scans your files, finds every filename that exceeds the ecryptfs limit, and lets you rename them — all from a clean Mac app.
Download SynoTrimmer — $29 USD
The problem
Synology encrypted shared folders use ecryptfs, which wraps each filename in an encryption layer. That layer expands the filename length, reducing the effective limit to 143 characters — well below the standard 255-character filesystem limit. Files with longer names fail to copy, often with unhelpful error messages.
Hunting through hundreds of files manually to find the offending names is not a workflow. SynoTrimmer is.
How it works
1. Point SynoTrimmer at a folder Select the folder you want to copy to your Synology encrypted volume. SynoTrimmer recursively scans every file and subdirectory.
2. Review the offending files Every filename exceeding the ecryptfs limit is listed clearly — showing the current length and how much needs to be trimmed.
3. Rename and go Rename files directly inside the app. Preserve file extensions and as much of the original name as possible. Then copy to your NAS without errors.
Features
- Recursively scans nested folders so no problematic filename slips through
- In-app renaming — no Terminal, no scripts
- ecryptfs-aware limits, not just the raw filesystem limit
- Preserves file extensions and meaningful parts of names when shortening
- Native macOS app — fast, lightweight, no subscription
- One-time purchase
FAQ
What is the filename length limit on Synology encrypted volumes? Synology encrypted shared folders use ecryptfs, which adds an encryption wrapper to each filename. This reduces the effective limit to 143 characters. Files with longer names will fail to copy with an error.
Does this work with all Synology NAS models? SynoTrimmer runs on your Mac and scans local files before you copy them to your NAS. It works regardless of your Synology model or DSM version — any Synology encrypted shared folder using ecryptfs has the same filename limit.
What macOS versions are supported? macOS 12 Monterey and later.
Why does macOS show a security warning when I open it? SynoTrimmer is not yet signed with an Apple developer certificate. To open it, go to System Settings → Privacy & Security and click Open Anyway after the first launch attempt. This is a standard macOS prompt for apps from independent developers.
Is there a trial version? Not currently. If you have questions about whether SynoTrimmer will solve your specific problem, get in touch before purchasing.
Download SynoTrimmer — $29 USD
One-time purchase · macOS 12+ · Instant download