Cache and CSP Issues with Extension on Firefox 42 Version

[Vamshi_Krishna]

I’m encountering problems with an extension I’m developing for Firefox 43. The extension installs but fails to work correctly, and I see multiple errors in the Browser Console:

1. Cache Errors :

• “Search failed when adding add-ons to cache.”
• “No element found” related to the extension GUID.

2. Content Security Policy (CSP) Warnings :

• Warnings about unknown CSP directives and invalid report URIs.

3. Strict-Transport-Security Warning :

• “The site specified a header that could not be parsed successfully.”

These issues do not occur on Firefox 56, but Firefox 43 is required for compatibility with older systems. I have cleared the cache, updated the manifest, and tried both chrome and browser APIs, but the errors persist.

Could you provide any guidance on making this extension fully compatible with Firefox 42?

Thank you for your help.

Here is the my xpi file: https://drive.google.com/file/d/1GnzAJ_Fb-La655L6coydg2_pO6--r9mQ/view?usp=sharing

[Vamshi_Krishna]

[juraj.masiar]

Does Firefox 43 actually support modern webextensions?

They were officially fully supported only when Firefox 57 was released (well, 57 disabled old addons).

Looking at the MDN, first WebExtension API seems to have arrived around version 48: https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/manifest.json#browser_compatibility

I really hope you don’t plan to visit online websites with such an old Firefox , it has like 9 years worth of security holes in it.

[Vamshi_Krishna]

But My site is doesn’t work on Mozilla 43 or later. Is there any alternative.