---
title: "PDF.js in Joomla: errors and troubleshooting - WebTolk websites development, Joomla Extensions"
description: "JSON is awaited for up to five seconds. Network/HTTP errors, redirects, invalid JSON, array roots and invalid names fall back to standard PDF.js behavior.…"
url: "https://web-tolk.ru/en/dev/joomla-plugins/wt-pdf-js/documentation/troubleshooting"
date: "2026-10-09T19:21:38+00:00"
language: "en-GB"
---

## Breadcrumbs

[Home](https://web-tolk.ru/en) > [Joomla extensions](https://web-tolk.ru/en/dev) > [Joomla plugins](/en/dev/joomla-plugins) > [WT PDF.js](/en/dev/joomla-plugins/wt-pdf-js) > [Documentation](/en/dev/joomla-plugins/wt-pdf-js/documentation) > PDF.js in Joomla: errors and troubleshooting

# PDF.js in Joomla: errors and troubleshooting

WT PDF.js - Documentation

**Category:** [Joomla plugins](https://web-tolk.ru/en/dev/joomla-plugins)

[Project](https://web-tolk.ru/en/dev/joomla-plugins/wt-pdf-js)[Versions](https://web-tolk.ru/en/dev/joomla-plugins/wt-pdf-js/versions)[Documentation](https://web-tolk.ru/en/dev/joomla-plugins/wt-pdf-js/documentation)[GitHub](https://github.com/mozilla/pdf.js)

JSON is awaited for up to five seconds.

## Diagnose assets, PDF files and configuration

JSON is awaited for up to five seconds. Network/HTTP errors, redirects, invalid JSON, array roots and invalid names fall back to standard PDF.js behavior. Search the console for `[WT PDF.js user-config]`. Invalid individual options do not prevent other accepted values from applying.

| Symptom | Check |
| --- | --- |
| Unknown asset | Installed/enabled plugin, code after registration, explicit registration in administrator pages. |
| pdfjsLib is undefined | Asset activated, consumer waits for the library, server/CSP allows .mjs. |
| Worker version mismatch | One build per window, matching library/worker, clear stale caches. |
| PDF will not open | Encoded file value, file exists, matching origin; endpoint returns PDF rather than login HTML. |
| JSON ignored | Network: correct URL and 200 JSON; lowercase .json, flat object, correct types; console warnings. |
| Different zoom | Check #zoom and viewOnLoad: fragments and document history affect startup. |
| Missing fonts/images | Matching cmaps, standard_fonts, wasm and iccs are available; paths account for subdirectories. |
| Unreadable code in dark Joomla | Use matching bg-body and text-body, without forced bg-white. |

Serve .mjs with a JavaScript MIME type. Open viewers over HTTP(S), not file://. Iframe sandbox restrictions on scripts or origin may prevent module/JSON loading. During troubleshooting, open the same viewer URL in a separate tab.

## JSON-LD Schema

```json
{
    "@context": "https://schema.org",
    "@type": "BreadcrumbList",
    "@id": "https://web-tolk.ru/#/schema/BreadcrumbList/17",
    "itemListElement": [
        {
            "@type": "ListItem",
            "position": 1,
            "item": {
                "@id": "https://web-tolk.ru/en",
                "name": "Home"
            }
        },
        {
            "@type": "ListItem",
            "position": 2,
            "item": {
                "@id": "https://web-tolk.ru/en/dev",
                "name": "Joomla extensions"
            }
        },
        {
            "@type": "ListItem",
            "position": 3,
            "item": {
                "@id": "/en/dev/joomla-plugins",
                "name": "Joomla plugins"
            }
        },
        {
            "@type": "ListItem",
            "position": 4,
            "item": {
                "@id": "/en/dev/joomla-plugins/wt-pdf-js",
                "name": "WT PDF.js"
            }
        },
        {
            "@type": "ListItem",
            "position": 5,
            "item": {
                "@id": "/en/dev/joomla-plugins/wt-pdf-js/documentation",
                "name": "Documentation"
            }
        },
        {
            "@type": "ListItem",
            "position": 6,
            "item": {
                "name": "PDF.js in Joomla: errors and troubleshooting"
            }
        }
    ]
}
```

```json
{
    "@context": "https://schema.org",
    "@graph": [
        {
            "@type": "Organization",
            "@id": "https://web-tolk.ru/#/schema/Organization/base",
            "name": "WebTolk",
            "url": "https://web-tolk.ru/",
            "logo": {
                "@type": "ImageObject",
                "@id": "https://web-tolk.ru/#/schema/ImageObject/logo",
                "url": "https://web-tolk.ru/images/webtolk-1080p.jpg",
                "contentUrl": "https://web-tolk.ru/images/webtolk-1080p.jpg",
                "width": 1920,
                "height": 1080
            },
            "image": {
                "@id": "https://web-tolk.ru/#/schema/ImageObject/logo"
            },
            "sameAs": [
                "https://github.com/WebTolk",
                "https://github.com/sergeytolkachyov",
                "https://vk.com/web_tolk",
                "https://vk.com/webtolkru",
                "https://tenchat.ru/sergeytolkachyov",
                "https://t.me/sergeytolkachyov",
                "https://t.me/webtolkru"
            ]
        },
        {
            "@type": "WebSite",
            "@id": "https://web-tolk.ru/#/schema/WebSite/base",
            "url": "https://web-tolk.ru/",
            "name": "WebTolk websites development, Joomla Extensions",
            "publisher": {
                "@id": "https://web-tolk.ru/#/schema/Organization/base"
            }
        },
        {
            "@type": "WebPage",
            "@id": "https://web-tolk.ru/#/schema/WebPage/base",
            "url": "https://web-tolk.ru/en/dev/joomla-plugins/wt-pdf-js/documentation/troubleshooting",
            "name": "PDF.js in Joomla: errors and troubleshooting - WebTolk websites development, Joomla Extensions",
            "description": "JSON is awaited for up to five seconds. Network/HTTP errors, redirects, invalid JSON, array roots and invalid names fall back to standard PDF.js behavior.…",
            "isPartOf": {
                "@id": "https://web-tolk.ru/#/schema/WebSite/base"
            },
            "about": {
                "@id": "https://web-tolk.ru/#/schema/TechArticle/base"
            },
            "inLanguage": "en-GB",
            "breadcrumb": {
                "@id": "https://web-tolk.ru/#/schema/BreadcrumbList/17"
            }
        },
        {
            "@type": "TechArticle",
            "headline": "PDF.js in Joomla: errors and troubleshooting",
            "url": "https://web-tolk.ru/en/dev/joomla-plugins/wt-pdf-js/documentation/troubleshooting",
            "description": "JSON is awaited for up to five seconds.",
            "mainEntityOfPage": {
                "@type": "WebPage",
                "url": "https://web-tolk.ru/en/dev/joomla-plugins/wt-pdf-js/documentation/troubleshooting"
            }
        }
    ]
}
```