Azure web app does not return not modified (304) when it should

Question

Azure web app does not return not modified (304) when it should

Enrico Sabbadin (MSC Technology Italia) 16

Etag and if modified since are sent correctly for a Js file .. still azure web app always returns 200 instead of 304.
How is that ? It works on iis

ajkuma 28,036 Reputation points Microsoft Employee Moderator

2022-09-26T19:58:11.637+00:00

EnricoSabbadinMSCTechnologyItalia-4455, Apologies for the delay from over the weekend.

Just to highlight – the HTTP code: 304 - Not Modified – Indicates that the URI requested has not been modified since the client last requested it.
This will usually mean that the client uses a cached copy of the resource.

So, the redirect URL returned to the client appears in the browser's address bar when the client makes a new request for the resource.

As you mentioned it works locally/IIS fine. Ensure that the web.config is added in the root and that in the web.config file, it redirects to “/index.html” and instead of “/”:

Also, please see this blog by Zain Rizvi for the detailed steps on Redirect URL and Rewrite.
example:
<configuration>
<system.webServer>
<rewrite>
<rules>
<rule name="Redirect rquests to default azure websites domain" stopProcessing="true">
<match url="(.*)" />
<conditions logicalGrouping="MatchAny">
<add input="{HTTP_HOST}" pattern="^test.azurewebsites.net$" />
</conditions>
<action type="Redirect" url="http://www.test.io/{R:0}" />
</rule>
</rules>
</rewrite>
</system.webServer>
</configuration>

Kindly let us know how it goes, I'll follow-up with you further.
Enrico Sabbadin (MSC Technology Italia) 16 Reputation points

2022-09-28T10:31:44.567+00:00

i quite don't get what redirect (302) has to do with my question with not modified (304)

1 answer

Your answer

ajkuma 28,036 Reputation points Microsoft Employee Moderator

2022-09-26T19:58:11.637+00:00

EnricoSabbadinMSCTechnologyItalia-4455, Apologies for the delay from over the weekend.

Just to highlight – the HTTP code: 304 - Not Modified – Indicates that the URI requested has not been modified since the client last requested it.
This will usually mean that the client uses a cached copy of the resource.

So, the redirect URL returned to the client appears in the browser's address bar when the client makes a new request for the resource.

As you mentioned it works locally/IIS fine. Ensure that the web.config is added in the root and that in the web.config file, it redirects to “/index.html” and instead of “/”:

Also, please see this blog by Zain Rizvi for the detailed steps on Redirect URL and Rewrite.
example:
<configuration>
<system.webServer>
<rewrite>
<rules>
<rule name="Redirect rquests to default azure websites domain" stopProcessing="true">
<match url="(.*)" />
<conditions logicalGrouping="MatchAny">
<add input="{HTTP_HOST}" pattern="^test.azurewebsites.net$" />
</conditions>
<action type="Redirect" url="http://www.test.io/{R:0}" />
</rule>
</rules>
</rewrite>
</system.webServer>
</configuration>

Kindly let us know how it goes, I'll follow-up with you further.
Enrico Sabbadin (MSC Technology Italia) 16 Reputation points

2022-09-28T10:31:44.567+00:00

i quite don't get what redirect (302) has to do with my question with not modified (304)

Answer 1

Thanks for the follow-up. Apologies for any confusion. The HTTP status codes 3xx – denotes Redirection. I was just sharing samples for Redirection, in general.

Just to clarify:
You have stated it works locally/on IIS, could you please share more details about your application framework/config?
How exactly are you reviewing HTTP code, via Fiddler or browser F12?
do you see fail to get the new code based on If-modified-since or ETAG. Does force refresh on browser - CTRL + F5 to force a download, shows any different behavior?

Typically, with 304 - The client browser requests a document that is already in the cache. And the document hasn't been modified since it was cached. The client browser uses the cached copy of the document instead of downloading the document from the server.

See if this works, Bundle Caching |
BundleTable.EnableOptimizations = true

Could you please check Failed request tracing and Web server logging to fetch more info. See troubleshoot-diagnostic-logs for the steps.

-- For detailed analysis on this, could you please share your WebApp name here or I’ll follow-up privately on this.

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Azure web app does not return not modified (304) when it should

1 answer

Your answer