---
type: concept
title: Web-compliant File Naming
created: 2026-07-01
updated: 2026-07-01
tags: [naming-conventions, unicode, troubleshooting]
related: [nextcloud]
sources: ["output/rz_uni_greifswald_de_dienste_webdienste_nextcloud_faq_nextcloud.md"]
---

# Web-compliant File Naming

Web-compliant file naming is the practice of avoiding characters that can cause encoding errors when processed by web servers and browser-based viewers.

## The Nextcloud PDF Viewer Issue
In the context of the URZ Nextcloud instance, a bug in the PDF viewer causes files to be reported as "Missing File" if the filename or any parent folder contains:
- **Spaces**
- **Special characters**
- **Umlauts** (e.g., ä, ö, ü, ß)

## Technical Cause
These characters are converted into Unicode encoding (percent-encoding). When the encoding becomes nested or complex (e.g., containing strings like `%25XXX`), the server may fail to resolve the actual path to the file, leading to a 404-style "Missing File" error.

## Recommendations
To ensure maximum compatibility with web-based viewers:
- Use alphanumeric characters.
- Use hyphens (`-`) or underscores (`_`) instead of spaces.
- Avoid non-ASCII characters (umlauts).
- If a file cannot be renamed, it can still be accessed by downloading it directly via the "three dots" menu instead of using the browser preview.