Filename, length, and file extension rules keep files compatible with external systems, reduce failed transfers, and enforce the naming requirements of your workflow. Applying them at upload time prevents disruptions before files enter automated workflows or downstream systems.

These restrictions apply when files or folders are placed directly into a folder. Ordinary move and copy operations succeed only when the destination path is no more restrictive than the source path. Archive Removed Files makes an exception to preserve existing content.

How Restrictions Are Enforced

Files.com provides built-in controls to enforce these requirements on uploads. You can limit uploaded files by filename length, restrict filenames using regular expressions, and allow or block specific file extensions. These settings apply at the folder level and can be inherited by subfolders, giving you precise control over how files enter your environment.

Filename restrictions check the name or extension, not the file's contents. A file with an allowed extension may still contain harmful content, and a valid filename does not protect the folder structure a workflow depends on. Use Malware Scanning for content inspection and folder structure locks when users must not move or rename the workflow's folders.

Moving or Copying Files into Restricted Folders

Ordinary move and copy operations fail when the destination path has filename-related restrictions that are stricter than the source path. This includes filename length limits, file extension rules, and regular-expression-based filename rules.

If any folder in the destination path enforces stricter rules, the system blocks the entire move or copy operation rather than validating each file.

This behavior is intentional. For protocols including SFTP, checking filename restrictions during move or copy operations would require inspecting every file in the operation, which would significantly slow transfers and reduce reliability. The system uses a fast-fail approach instead of per-file validation. If a destination folder enforces a stricter filename length or extension rule than the source, the move or copy operation fails immediately rather than checking each file.

To prevent move or copy failures, do not configure stricter filename length, file extension, or regular-expression-based rules on folders when files need to be moved or copied into those locations.

Archive Removed Files disregards these destination rules, whether configured directly or inherited, so they do not prevent deleted or overwritten content from being preserved. Ordinary uploads, moves, and copies into that same archive folder still follow their existing restrictions. Files.com's path requirements also continue to apply to archive moves.

Automations and Renaming Considerations

For Automations v1, configure source filename patterns and destination filenames on the action. For Automations v2, use file selection on the trigger and destinations and templates on the nodes. Use the settings for your version to ensure the resulting names meet the destination folder's restrictions.

Naming and Folder Structure Requirements

Choose filename rules for the receiving system's actual constraints. For a feed that expects CSV filenames with a date and partner identifier, combine an extension limit with a regular-expression rule. If a destination has a filename-length limit or cannot accept particular characters, apply those requirements to the intake folder before files enter the transfer flow. An allowed name does not establish that the contents have the right format; Expectations content validation can check structured data against your rules.

Use folder structure locks when an application, Sync, or Automation depends on a stable path. The lock protects that arrangement from folder moves or renames while permitted file operations continue. Filename restrictions and folder locks address different sources of disruption, so choose each for the dependency it protects.