Fetching of appcache failes in firefox

Question

Fetching my appcache fails in firefox: it starts downloading my items, but at around number 60 or 70 (number varies between runs) out of my 1000 items, the fetching stops and I receive an appcache error. How can I properly debug this, to see what file causes this error? Because the item number varies between runs, I don't exactly know which file I should be looking at.

Answer 1

• In Firefox press Shift > F2 to open the GCLI command line
• Go to your webpage
• In the Firefox command line type appcache clear
• In the Firefox command line type appcache validate

Any errors will be displayed.

Answer 2

Tools which are useful for debugging are this one (which is essentially just logging the appcache events), and Manifesto. However, both tools do not provide feedback on which file in my appcache causes this error. Manifesto verifies my appcache as 'ok', even though my firefox fails to fetch the files

The only way to detect the error in my manifest file was removing items from my manifest, until I was left with a single item (a .jsp file) responsible for the error. The cause of the error turned out to be the Cache-Control header, which had a 'no-store' value. Apparently only firefox honours this header. Removing the no-store value (values such as must-revalidate and no-cache are allowed) fixed this issue.

ps. I've filed a bug report for Manifesto, so hopefully it will throw an error for this use-case in a future Manifesto version