[Zope] zip files corrupted with IE when opened, fine when downloaded

[Jim Washington]

Jim Washington wrote:
> robert rottermann wrote:
>> Hi there,
>> we have a problem with an intranet that runs using plone 2.5.3
>>
>> when users using IE want to open a zip file from the intranet by using
>> the "open" option from the download dialog they get winzip complaining
>> that the file is corrupted.
>> if they select "save" from the same dialog they can open the zip archive
>> without problem.
>>
>> does anyone know a solution for this or give me an idea where to look
>> for one?
>>   
> I had a similar problem with pdf files, and googling indicated that IE 
> might be deleting the cached copy of the document before the opening 
> application can get to it.
>
> I have had some success setting cache control to "private".  Something 
> like:
>
> request.response.setHeader('cache-control','private')
>
> "private,must-revalidate" may also be a good value, depending on your 
> situation.
>
I Googled back through and found that the problem usually manifests when 
you have a 'cache-control':'no-cache' header.  The above explanation was 
not quite right.

Anyway, either removing the "no-cache" header or using one that allows 
the local machine to keep a copy should work, if the problem is in fact 
a 'no-cache' header.

- Jim Washington