Vue.js is a popular JavaScript framework that allows developers to create single-page applications with dynamic user interfaces. However, integrating external libraries like jQuery or Bootstrap can sometimes cause issues due to their different dependency management systems.

Here are some tips for troubleshooting Vue.js external library integration:

1. Use the correct order of scripts: Make sure that your external libraries are loaded before your Vue.js app is initialized. You should load jQuery and Bootstrap first, followed by Vue.js.

2. Avoid using .noConflict(): If you're using jQuery and another library that also uses $, try to avoid using the noConflict method to avoid conflicts. Instead, use $ as a shortcut for jQuery.

3. Use proper Vue.js component integration: If you are using an external library like Bootstrap, it may have components like modals or dropdowns that need to be integrated into your Vue.js app. Make sure to follow the documentation and integrate them properly.

4. Check for any errors in the console: Use the browser's developer tools to check for any errors that occur when loading or using the external library. These errors can give you clues as to what might be causing issues with the integration.

5. Check if there are any known compatibility issues between your library and Vue.js: Look up any known issues or compatibility problems between your chosen library and Vue.js on GitHub, Stack Overflow, or other forums. This can help you troubleshoot and identify potential solutions.

Remember to test your integration thoroughly after making changes to ensure that it works as expected.