Ok, I'm building a PoC for an ASP.NET MVC 4 mobile application that needs to have offline capabilities, and I have several questions about whether I'm designing the application correctly and also what behavior I will get from the cache manifest.
I'm progressing with the PoC but I'm observing a weird behavior on a working controller action right after adding the manifest attribute to my Layout.cshtml.
Before adding the attribute, every time I requested that URL, a breakpoint I had on the controller action would be hit just once every time. After adding it, the breakpoint is being hit 3 times the first time the page is requested (first time ever), and it is no longer hit at all until I manually delete the local cached manifest.
Nothing else changed, so this makes me believe that this type of offline caching works differently that the regular way in which browsers cache works. I'm thinking that since the page I'm visiting is listed on the manifest, the breakpoint is hit the first time because I requested the page, and then a second time because it is listed on the manifest.
That is weird already. Why is that?
Besides that, why is it being hit a third time?
I've verified that the behavior goes away if I manually delete the locally cached manifest and also remove the manifest attribute from the html tag, so this is most likely the culprit.
Can anyone explain what's going on please? Thanks.
Well, no one replied and I was no longer able to reproduce the breakpoint being hit 3 times, although I'm sure it happened a few times.
And yes, appcache or html manifest caching works in a different way than regular caching.
With the first visit a page, that had the manifest attribute on its html tag, the same page being listed on the manifest made a request to the server for the same page.
I'm making the answer a wiki in case someone wants to add anything.
Related
The Problem
I have a website running in IIS. If I rename or delete one of the layout page .cshtml files under /Views/ the site immediately begins throwing following yellow screen error as expected
The layout page "_Layout.cshtml" could not be found at the following path: "~/Views/_Layout.cshtml".
What surprises me is that if I recreate or rename the file so it is exactly like it was before, the yellow screen persists. Why is this particular 500 error sticky?
I currently think that this has something to do with IIS and is specifically related to error handling. The site immediately detects that the layout page file is missing. It does not immediately realize when the file is back in place.
Thanks!
Some interesting clues
This happens on all of my sites I've tried this on so far. It isn't related to a specific site
I tried this on two websites at the same time. On one site I repeatedly and consistently refreshed the page hoping for a success. On the other, I left it alone for several minutes before checking again. The site I leave alone will resolve its problems and find the layout page on disk again. The site I continually make requests to appears to display the error indefinitely.
What I've tried
I have reproduced the problem on Umbraco websites using Umbraco's default routing as well as regular MVC pages using custom routing. The problem is the same for both.
I don't have output caching configured in IIS
When I am reproducing the yellow screen error, I am able to reproduce the error in multiple browsers, so I don't believe it is related to browser caching
I checked on the httpRuntime in the root web.config and the fcnMode is set to fcnMode="Single"
I've fiddled around with the web.config customErrors and httpErrors. Nothing I've done here has affected the problem.
I am able to reproduce the problem on websites where there is no custom code for caching. No CDN. No load balancer.
Versions
IIS: I have reproduced the problem on Windows Server 2012R2 running IIS 8 and Windows 11 running IIS 10
CMS: All of the websites I have tested on so far are Umbraco 7 sites. However, I have reproduced the problem on pages that are routed using Umbraco's out of the box routing as well as pages that are just set up using MVC and aren't leveraging Umbraco.
It appears to be part of the behavior of FcnMode="Single". See https://learn.microsoft.com/en-us/dotnet/api/system.web.configuration.fcnmode?view=netframework-4.8. It isn't an issue with caching. It is a problem with the way that the site's file change notifications (FCN) are configured.
The sticky 500 behavior on renaming files happens when I use FcnMode="Single" but not when I use FcnMode="Default".
FcnMode="Single" will result in only a single object to monitor file changes. This single object is responsible for monitoring changes to files in the main directory and sub directories.
FcnMode="Default" will result in a separate object to monitor file changes for each directory.
Umbraco sites, by default, use FcnMode="Single". This makes sense because Umbraco sites cache under very deeply nested directories in /App_Data/. This can result in so many of these monitors that it can affect the performance of the site. There is a great explanation of FcnMode and why it matters for Umbraco here: https://shazwazza.com/post/all-about-aspnet-file-change-notification-fcn/
Unfortunately, it appears that the single file monitor can miss renames of files in some cases.
I've met a very strange bug when tried to open my web site http://akr-congress2016.ru/ in iOS Safari. Please see the screenshot below.
It seems like some elements are loaded from a completely other web site. The new site is a copy of the old one, but layout files (I'm using Phalcon) are changed. There is no link to the old web site at the page.
Also I've noticed doubled logo, it seems like a rendering bug.
When I refresh the page it is loaded normally.
I'm weird what might make Safari to load some fragments of the page from completely another domain.
The screenshot
Try to remove cache from browser. Or maybe it's just an issue of DNS. In that case you just need to wait untill DNS will get updated.
I have an MVC 5.x app which has had its views precompiled and merged into a single assembly. Even after all this the first request to a view after AppDomain startup is slow, it does not matter which view is requested as they are all slow the first time the view is requested. Digging in with MiniProfiler I can see it is the "Render" time on the view which takes the majority of the time and upon additional requests to the view the Render time is reduced by about 90%. So to be clear it is this first-time Render that is taking allot of the time. I was not expecting to see this bit of slowness due to the fact all of views have been precompiled and I do not believe it is the JIT that is causing this massive slow down...anyone have any guesses or insights?
Please note, this is not the very first request of a web application, this is the first request of a particular view/page. For example, for the test below the app had been running for hours and was taking requests constantly but the test captured the first request for this view.
First Request
Second Request
Strange! In order to be 100% sure what exactly happens, however, I'd do the following:
I'll redirect the run-time compilation (yes, there'll be one since at
least Global.asax needs to be compiled) like this:
<system.web>
<compilation debug="true" targetFramework="4.5" tempDirectory="c:\temp\asp.net" />
...
</system.web>
I'll investigate the contents of the folder before and after the
first run. Maybe it'd be even better to have a copy of the original.
From your description of the problem it seems like everything should be just fine and there would be no differences between the runs. Still comparing contents of the folder before and after may reveal some difference.
Another cause might be some caching but I can guess you have already sorted this up.
I struggled with the exact same issue for months: It happened to me in some views only.
Apparently, the rendering of the views is not that straightforward as I thought, since MVC needs to run a couple of operations to determine the exact .cshtml to use for an action, its partial views if you have any, etc etc.
What did the job for me is to use Razor Generator which processes Razor files at design time instead of runtime. (if you wanna give it a shot, I suggest first trying it with a view you know takes time to load at first attempt).
From the website:
One reason to do this is to avoid any runtime hit when your site
starts, since there is nothing left to compile at runtime. This can be
significant in sites with many views.
The downside of implementing the Razor Generator is that you no longer need the .cshtml files: so if you want to change a view, you have to recompile the project. But that's not an issue necessarily, at least not for me.
Install the Razor Generator from the VS extension gallery first (like it's explained on the website) and then the nuget package.
Trust me: you are gonna be so relieved you're gonna cry ☺
I am running an instance of Umbraco 6.1.x and it has started throwing 404 on published pages.
My page structure is as follows,
Content
Home
About
Course
...
Component
Home
About
Course
Where component holds all resources and modules (HTML sections and stuff) for a page and using a partial view macro I dynamically load all components at runtime for a specific page.
We are facing an issue where we get 404 on every page after a full republish once we hit the HomePage. Before hitting home page they are all fine, but the moment we hit the homepage they are all throwing 404. By overriding the handlers I found out that they are hitting ~/umbraco/RenderMvc!
Any idea what can cause this?
Thanks in advance.
EDIT:
It is actually throwing:
No template exists to render the document at url '/'
considering the aforementioned scenario.
I have proper allowed template setup and property on nodes are showing the correct template associated with the respective items. Not sure why it's losing template info. I can force it to load under correct template using ?altTemplate=templateName.
Some pointers, we have a view in Views/Shared folder (apart from macro partials) tied to a surface controller.
One thing I would like to say is, we are using nested (library.RenderMacroContent with Umbraco markup) in our partial views and I have realized that the whole page throws 404 if there's a page with a link to the broken page which is broken (i.e. page got re-created and on t==e of the components is holding a link to the page with previous id). Suggestions?
did you get to the bottom of this? We're having exactly the same problem at the moment, on the same version of Umbraco.
I've noticed that when it happens, the umbraco.config becomes either corrupt or rolls back to a much, much earlier version, with all sorts of attributes missing. This lead us to believe it was a sync issue between the DB and umbraco.config.
We initially thought we had solved it by deleting App_Data > TEMP > ExamineIndex and recycling the app pool etc. Maybe give this ago, as it fixed it for a while for us, but alas, the demon has reared its ugly head once more. We are still in a full on dev stage though, so the constant changing may be complicating it further for us - perhaps it will be a fix for you.
If you have any more info, or even a fix, it would be greatly appreciated.
Cheers
EDIT:
Ok, I think I've solved this now, but only time will tell. Try emptying your recycle bin & then republish entire site.
I managed to consistently recreate the bug using IIS SEO site analysis. Each time I did this, the log threw up an error 'cannot find node id xyz', turns out that (and other) nodes were in the recycle bin. Upon emptying it the errors stopped. Good luck!
I am working on a test application based on ASP.NET MVC. I am new to CSS stuff so I am learning that as well.
I have created a master page called "new.master" and created a new css "new.css". I am calling the view from controller as:
return View ("About", "new");
What I am doing is that I am frequently updating the css and master page. So I run the application in debug mode frequently. After sometime I stop seeing the effect of changes in css. When I "view source" in chrome and check the css, it shows an old version.
When I change the name of both master page and css, I start to receive updated views but that works for sometime and then again I stop getting the CSS updates. Have you faced this problem? How can I fix it? (Its terribly annoying!)
Your browser is caching the css. If you force a refresh with F5 that should display any changes.
I think this may be a browser cache issue. In in IE and FF I usually do Ctrl + F5 or Ctrl + Refresh button. Also you can manually clear the cache. For IE you can use the IE Dev Toolbar and for Firefox there is Firebug with both you can clear the cache easily. Not sure about chrome, sorry.
Sayed Ibrahim Hashimi
My Book: Inside the Microsoft Build Engine : Using MSBuild and Team Foundation Build
I found another case in which this can happen.
We started our application with just plain links to the CSS files, then switched to using bundling. We updated the old <link href="#Url.Content("~/somePath/someStyle.css")" rel="stylesheet" type="text/css" /> to #Styles.Render("~/Styles/bundles/someStyle").
We also use a few stylesheets which are only needed for some pages, and they have their own bundle. Now, for one of them, we forgot to change the link tag to the #Styles.Render statement.
The result was that this CSS got updated now and then (so we thought everything is OK; the style wasn't missing), but we could not influence when the update happens. When I started making changes to the file, I realized that nothing I do (emptying the cache, rebuilding the project, restarting Cassini) will trigger an update. The browser always got a 304 Not modified.
So, if you have these symptoms, check your links.
Please use Ctrl+F5 to refresh your browser.
F5 may give you the same page even if the content is changed, because it may load the page from cache. But Ctrl - F5 forces a cache refresh, and will guarantee that if the content is changed, you will get the new content.
hope this will help you
Thank you
go to chroom developer panel by right click inspect -> then go to Network tap -> tick the Disable cache checkbox (note: this should always be checked) -> Refresh the page by pressing F5.
this work for me, hope this help others who have this issue! :)
It's very possible that css is being cached in your browser, so simply clearch browser cache, it should help
This happened to me when I had a master view that would load partial views depending on which partial view the user wanted to see, but the answer from this page helped, https://forums.asp.net/t/1763494.aspx?applying+CSS+layouts+to+a+partial+view
CSS must be referenced in the of the Html document. As a
consequence you cannot include them in a partial view...because in
such case the css is included in the Html body. Please plce the style
sheet in head of the page that hosts the partial view.
I would have css links in my partial views and any modifications to the css files would never happen, even if I pressed Ctrl-F5 in the browser. I also tried clearing cache contents in the developer tools. I noticed by viewing the source stylesheets that the css files linked by the partial views were not changing, so the fix for me was to move the css links from the partial view to the main view where these partial views were to be held.
I had something similar happening to me.
Then suddenly noticed the bundle was added to the page:
#Styles.Render("/bundles/classifiedDetailCss")
instead of:
#Styles.Render("~/bundles/classifiedDetailCss")
Note the missing ~ character in the first example.
(The first example only worked after building the project, otherwise it would return a cached version even in debug mode.)
This can help solve this issues in both dev and production.
use asp-append-version="true"