| Re: totally WEIRD bug? Firefox caching? [message #185371 is a reply to message #185366] |
Thu, 20 March 2014 14:53   |
Arno Welzel
Messages: 317
Registered: October 2011
Karma:
|
Senior Member |
|
|
Am 20.03.2014 12:26, schrieb The Natural Philosopher:
> On 20/03/14 09:13, Arno Welzel wrote:
>> Am 19.03.2014 18:25, schrieb The Natural Philosopher:
>>
>>> I have TWO IDENTICAL PHP FILES.
>>>
>>> They are supposed to display an image got from a database.
>>>
>>> One does. The other does not.
>>>
>>> It persistently tells me the image is corrupted.
>>>
>>> I have even copied one file that works directly over the other. It still
>>> doesn't work.
[...]
> What is happning - and oddly running it against a test version of IE6 in
> my XP VM showed it up, was that it was outputting a '404 file not found'
> text BEFORE outputting perfectly valid PNG.
>
> Why this is happening is a bug somewhere else completely.
>
> IE 6 simply showed the text and the binary gobbledygook which was the
> clue I needed.
Yes, because IE 6 assumes the user may not understand a server generated
error message and shows its own message as long as the reponse is below
a certain size limit (AFAIR less than 4000 bytes, but i may not remember
correctly). This is even more annoying - sometimes you see the message
from IE itself and sometimes
> How this has happened will take me some time to understand because the
> line that says '404 not found' is followed - or I thought it was - by
> an exit(); statement.
>
>> Either Firefox once got an invalid image and cached the response or the
>> server does not respond the way you think. Maybe a BOM in the PHP file?
>> This may not be visible in your editor, but it can cause all sort of
>> problems.
>>
>>
> Firefox makes it hard to debug because it DOES cache bad results: I
> usually fix that by sending random nonsensical GET parameters which are
> ignored to ensure it thinks its a different URL each time.
>
> It a huge minus against firefox that it didn't - even using the
> debugging console - show me what was really going on, whereas IE6 did.
You should learn to read HTTP response headers in the developer console
of Firefox. When I open <http://arnowelzel.de/wiki/en/tools/rwinfo>
there the developer console of Firefox tells me EXACTLY what is going on:
1) The server responded with a status code 404 (not found)
2) The response contains a number of headers which are also displayed
--
Arno Welzel
http://arnowelzel.de
http://de-rec-fahrrad.de
|
|
|
|
Calendar
Search
Help
Members
Register
Login
Home
]