Closed Bug 675602 Opened 13 years ago Closed 12 years ago

Web console show "Cannot show responses of type «(null)»" for 304 "Not modified" responses


(DevTools :: General, defect)

Not set


(Not tracked)



(Reporter: tonn81, Unassigned)




User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:5.0) Gecko/20100101 Firefox/5.0
Build ID: 20110622232440

Steps to reproduce:

0. Opened Firefox
1. Opened web console
2. Enabled logging of requests/responses
3. Opened site that does 304 responses
4. Clicked on that request in web console
4. Scrolled down to the response content block

Actual results:

See "Cannot show responses of type «(null)»" in response content block

Expected results:

Response content block should show «(null)».

Also it would be great there one more field appear that would show actual value given to browser core (taken from cache).
Mozilla/5.0 (X11; Linux i686; rv:8.0a1) Gecko/20110802 Firefox/8.0a1

Artem, can you please provide a link to a website that generates 304 responses?

Sample of the 304 page that produces the same bug is
Mozilla/5.0 (X11; Linux x86_64; rv:9.0a1) Gecko/20110822 Firefox/9.0a1

The actual result for me is: <<Unable to display responses of type "(null)">> in "unknown content type" tab. 

Taking the last phrase from comment 0 into consideration, Artem, would this rather fit as an enhancement issue?
(In reply to Virgil Dicu from comment #3)
> Taking the last phrase from comment 0 into consideration, Artem, would this
> rather fit as an enhancement issue?

This is a bug as in the worst case it should show "(null)"  instead of this "Unable to display" message. That might also lead to some mem leak or security hole. Please confirm it as you reproduced that.

As of my comment - there are two ways to show that response and I'm not sure what is more suitable:
 * show response as is (i.e. "(null)")
 * show actual content given to JS (i.e. the previous content)

It would be great if we show both.
Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:9.0a1) Gecko/20110829 Firefox/9.0a1
Mozilla/5.0 (X11; Linux i686; rv:9.0a1) Gecko/20110818 Firefox/9.0a1
Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:9.0a1) Gecko/20110829 Firefox/9.0a1
Mozilla/5.0 (Windows NT 5.1; rv:9.0a1) Gecko/20110829 Firefox/9.0a1

Reproducible on Ubuntu 11.04, Windows XP and 7, Mac X OS 10.6 using the site provided in comment 2.


1. Open Firefox
2. Open web console
3. Enable logging of requests/responses (right click web console)
3. Open site that does 304 responses (
4. Reload the web page.
5. Click the last request.

Actual result: <<Unable to display responses of type "(null)">> under "unknown content type"

Expected results: Cached image

Last good nightly: 2011-01-11
First bad nightly: 2011-01-12

Ever confirmed: true
OS: Linux → All
Hardware: x86_64 → All
Version: 5 Branch → Trunk
found this during triage. This appears to be fixed. Closing.
Closed: 12 years ago
Resolution: --- → FIXED
Product: Firefox → DevTools
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