Agent Skills: Obsidian Common Errors

Obsidian Common Errors

Overview

Diagnostic guide for the six most frequent Obsidian plugin development errors, with root causes and copy-paste fixes.

Prerequisites

• Obsidian plugin development environment set up
• Access to Developer Console (Ctrl/Cmd+Shift+I)
• Plugin source code access

Instructions

Step 1: "Cannot read properties of null" — Workspace Not Ready

Accessing app.workspace.activeLeaf or app.workspace.getActiveViewOfType() before the layout is initialized returns null.

// BROKEN: accessing workspace immediately in onload
async onload() {
  const view = this.app.workspace.getActiveViewOfType(MarkdownView);
  // TypeError: Cannot read properties of null (reading 'editor')
  view.editor.replaceSelection('hello');
}

// FIXED: wait for layout-ready event
async onload() {
  this.app.workspace.onLayoutReady(() => {
    const view = this.app.workspace.getActiveViewOfType(MarkdownView);
    if (view) {
      view.editor.replaceSelection('hello');
    }
  });
}

For commands that need workspace access later (not at load time), guard with a null check:

this.addCommand({
  id: 'my-command',
  name: 'Do Something',
  checkCallback: (checking: boolean) => {
    const view = this.app.workspace.getActiveViewOfType(MarkdownView);
    if (view) {
      if (!checking) {
        // safe to use view.editor here
        view.editor.replaceSelection('inserted');
      }
      return true;
    }
    return false;
  }
});

Step 2: "Plugin failed to load" — Syntax or Manifest Errors

This error appears in the console when Obsidian cannot parse your built main.js or your manifest.json is invalid.

Check 1: Build output exists and compiles cleanly

set -euo pipefail
npm run build 2>&1
# Look for TypeScript errors in output
ls -la main.js  # Must exist in plugin root

Check 2: manifest.json has all required fields

{
  "id": "my-plugin",
  "name": "My Plugin",
  "version": "1.0.0",
  "minAppVersion": "0.15.0",
  "description": "Does something useful",
  "author": "Your Name",
  "isDesktopOnly": false
}

Missing id, name, version, or minAppVersion causes a silent load failure. The id must match the folder name under .obsidian/plugins/.

Check 3: Default export

// BROKEN: named export
export class MyPlugin extends Plugin { ... }

// FIXED: default export required
export default class MyPlugin extends Plugin { ... }

Step 3: CSS Not Loading — Wrong styles.css Path

Obsidian auto-loads styles.css from the plugin root directory. It must be named exactly styles.css (not style.css, not in a subdirectory).

set -euo pipefail
# Verify all three required files exist in plugin root
ls -la styles.css manifest.json main.js

If you use a CSS preprocessor, ensure the build outputs to ./styles.css:

{
  "scripts": {
    "build:css": "sass src/styles.scss styles.css",
    "build": "npm run build:css && node esbuild.config.mjs"
  }
}

Common gotcha: the file must be styles.css (plural), not style.css.

Step 4: Commands Not Showing in Palette

Commands registered outside onload() or after the plugin is enabled won't appear in the command palette.

// BROKEN: adding command in a separate method called conditionally
async onload() {
  await this.loadSettings();
  // command never added because registerCommands is not called
}

registerCommands() {
  this.addCommand({ id: 'test', name: 'Test', callback: () => {} });
}

// FIXED: add all commands directly in onload
async onload() {
  await this.loadSettings();

  this.addCommand({
    id: 'test',
    name: 'Test',
    callback: () => {
      new Notice('Working!');
    }
  });
}

If a command should only be available when a markdown file is open, use editorCallback instead of callback — Obsidian automatically hides it when no editor is active:

this.addCommand({
  id: 'editor-only',
  name: 'Editor Only Command',
  editorCallback: (editor: Editor) => {
    editor.replaceSelection('inserted text');
  }
});

Step 5: Vault Read Errors — File Doesn't Exist

vault.read() and vault.cachedRead() throw if the file doesn't exist. Always check first.

// BROKEN: assumes file exists
async readConfig() {
  const content = await this.app.vault.adapter.read('config.json');
  return JSON.parse(content);
}

// FIXED: check existence, handle missing file
async readConfig(): Promise<MyConfig> {
  const path = 'config.json';
  const exists = await this.app.vault.adapter.exists(path);
  if (!exists) {
    return { ...DEFAULT_CONFIG };
  }

  try {
    const content = await this.app.vault.adapter.read(path);
    return JSON.parse(content);
  } catch (e) {
    console.error('Failed to parse config:', e);
    return { ...DEFAULT_CONFIG };
  }
}

For vault files (TFile objects), use getAbstractFileByPath:

const file = this.app.vault.getAbstractFileByPath('notes/target.md');
if (file instanceof TFile) {
  const content = await this.app.vault.read(file);
  // process content
} else {
  new Notice('File not found: notes/target.md');
}

Step 6: Settings Not Persisting — Missing saveData Call

The most common settings bug: modifying the settings object without calling saveData.

// BROKEN: settings change lost on restart
this.settings.theme = 'dark';
// forgot to call saveData!

// FIXED: always save after modifying
this.settings.theme = 'dark';
await this.saveData(this.settings);

In settings tabs, save on every change:

new Setting(containerEl)
  .setName('Theme')
  .addDropdown(dropdown => dropdown
    .addOption('light', 'Light')
    .addOption('dark', 'Dark')
    .setValue(this.plugin.settings.theme)
    .onChange(async (value) => {
      this.plugin.settings.theme = value;
      await this.plugin.saveSettings();  // calls this.saveData(this.settings)
    }));

Load settings with defaults to prevent undefined fields after plugin updates:

async loadSettings() {
  // loadData() returns null on first run — Object.assign handles this safely
  this.settings = Object.assign({}, DEFAULT_SETTINGS, await this.loadData());
}

Object.assign merges saved data over defaults, so new fields added in later versions get their default value instead of undefined.

Output

• Identified error matched to one of the six categories
• Root cause explanation
• Working code fix applied to plugin source

Error Handling

| Error | Cause | Solution | |-------|-------|----------| | TypeError: Cannot read properties of null | Workspace not ready | Use onLayoutReady or null-check | | Plugin failed to load | Build error or bad manifest | Check console, verify manifest.json fields | | CSS has no effect | Wrong filename or path | Must be styles.css in plugin root | | Command missing from palette | Not added in onload() | Move addCommand into onload | | Error: ENOENT on vault read | File doesn't exist | Check with adapter.exists() first | | Settings reset on restart | Missing saveData call | Call saveData after every mutation |

Examples

Quick Diagnostic Checklist

When a plugin fails to load, check these in order:

1. Open Developer Console (Ctrl/Cmd+Shift+I) and look for red errors
2. Verify main.js, manifest.json, and styles.css exist in plugin folder
3. Confirm manifest.json has id, name, version, minAppVersion
4. Confirm main.ts uses export default class
5. Rebuild with npm run build and reload Obsidian (Ctrl/Cmd+R)

Debug Logging Pattern

// Add to your plugin class for temporary debugging
private debug(msg: string, ...args: any[]) {
  if (this.settings.debugMode) {
    console.log(`[${this.manifest.id}] ${msg}`, ...args);
  }
}

Resources

• Obsidian Developer Docs
• Obsidian Forum - Developers
• Obsidian Plugin Guidelines

Next Steps

For comprehensive debugging workflows, see obsidian-debug-bundle.