I have a piece of code where I delete a file from the server. Sure, I could firstly check if file even exists and then delete it; and I've done it so. But, what really bothers me is why express.js app crashes when it wants to delete a file that doesn't exists? I get the 'Error: ENOENT, unlink'.
fs.unlink(path, function(err){
if (err) throw err;
});
If in the above code "path" does not exists, I get the "ENOENT" error and server crashes.
I thought "server.on('error', onError);" in www file handles such errors as well. Is it possible to add such a handler?
So you should just handle that error there. That's the place in code that knows best how to handle it and what caused it. The broader last-resort places are server.on('error', handler) but that's for errors within the express HTTP service processing logic itself, not any error in the entire node process. For any error in the process there's process.on('uncaughtException', handler).
why express.js does not handle such errors
Because express is not omniscient and the correct way to handle that error is only known to you. For all express knows, crashing the process IS the correct behavior.
Related
I'm using Ionic/Vue and wheen I run the application in my browser it works well but when I compile and run on an android emulator I get the error below. Please help
Error: Request aborted at e.exports (chunk-vendors.85bc3696.js:1) at XMLHttpRequest.m.onabort (chunk-vendors.85bc3696.js:26)
That error indicates that some of your vue components gets destroyed before ajax request gets completed. Check over all your code - everywhere you invoke remote service make sure that you 'await' result before allow anything to switch to another route, which leads to components disposal. Sometimes you need to do 'unsubscribe' from http request in component disposal
Actually, that probably is not an error - that is normal that request gets aborted if result is not needed anymore
I've been looking into New Relic, BugSnag, and a few others, but no one seems to be catching 404 errors in their client-side monitoring. For example, say I have the following script tag in a given page:
<script src="//cdn.example.com/app.js1445291270"></script>
with the minor but critical typo of missing a ? after .js.
This of course returns a 404 and the script never loads.
Are there any services that would catch client-side errors like this?
You should be able to do this with Bugsnag. You can detect whether the status= 404, and use Bugsnag.notifyException() to send the error in. Hope this helps!
TrackJS error monitoring supports this use case. Here is how to add monitoring for resource loading failures.
We are getting a 405 error and the following exception from IIS7 when attempting to apply a ResponseStreamFilter to HttpResponse.Filter:
HttpException:
The HTTP verb POST used to access path '/app/Thing.asmx/Command' is not allowed.
We are applying the filter by using an HttpModule with code like this:
var rfs = new ResponseFilterStream(HttpContext.Current.Response.Filter);
rfs.TransformStream +=
new Func<System.IO.MemoryStream, System.IO.MemoryStream>(ProcessStream);
HttpContext.Current.Response.Filter = rfs;
Log("Response stream filter applied correctly.");
All of the code in our HttpModule works just fine... it's all wrapped in a try-catch just to be safe and isn't throwing any exceptions, and diagnostic logging like the last line above is working correctly.
But it looks like our ProcessStream method in the above code is never being called. If we apply the filter to HttpResponse.Filter at all, IIS throws the 405 exception before our filter begins processing.
Our code has worked before on several similar systems, so we suspect IIS/machine configuration on this specific server is responsible. What could be causing this?
The most commonly reported cause for a 405 error in a situation like this seems to be using Url.Rewrite. (The HTTP verb POST used to access path '/test.html' is not allowed) However, we are never using a Url.Rewrite.
Another commonly reported cause is trailing slashes in the request URL. (HTTP 405 on Error on HTTP POST IIS ASP .NET) But as mentioned above, the URL being requested does not end with a slash.
The app pool is running .NET 4.0 in a Classic pipeline (jQuery AJAX post receives 405 error (HTTP verb POST not allowed)), but our code has run without issue on many other systems under a Classic app pool, so there would still have to be something unique to this server's configuration. Changing to Integrated pipeline breaks the application our code is filtering, so that's not a possible workaround anyway.
Turns out, it was a very obscure IIS bug:
http://support.microsoft.com/kb/980368
The ExtensionlessUrl handler (*.) was incorrectly getting involved with the request instead of just the WebServiceHandlerFactory (*.asmx) as expected. The workaround was:
Manually deleting the ExtensionlessUrl handler entries from the web application's handler mappings
Manually moving the ExtensionlessUrl handler entries under anything you actually expect to be hit
Adding a web.config entry under system.webServer/handlers to remove the ExtensionslessUrl handler as needed (we went with this option to make sure it got included with app demployment)
We had to burn a Microsoft support ticket on this one, since there's no way we would have figured this out in any reasonable timeframe. Hopefully this helps someone else.
Something is access my site using this URL:
/(Yvax:%20uggc:/jjj.tbbtyr-nanylgvpf.pbz/hepuva.wf)uggc:/jjj.tbbtyr-nanylgvpf.pbz/hepuva.wf
So I get error:
[error] [exception.CHttpException.404] exception 'CHttpException'
Is it something to worry about?
How can I stop YII from reporting on this specific error and other similar 404 errors that are unwanted?
Probably just a scanner script. We get hit by these all the time. Review security, but as long as that checks out you should be fine.
I have this code that it used to work, but at some specific time it stopped to work and returned the error "The remote server returned an error: NotFound."
WebClient deliciousWebClient = new WebClient();
deliciousWebClient.Credentials = Credentials;
deliciousWebClient.DownloadStringAsync(new Uri("https://api.del.icio.us/v1/tags/get"));
deliciousWebClient.DownloadStringCompleted += (s, ee) =>
{
if (ee.Error == null)
{
…
Any suggestion on this error?
In this code, the error is pointing to delicious endpoit, but the same error is happening with some other services...
The NotFound error is a classic 404 error, so it's possible that the API endpoint is down or that it changed on you.
I'd start by using Fiddler2 to make the requests manually. That'll help you figure out whether the issue is in your code somewhere or on the API side.
It's hard to get Fiddler working with the WP7 emulator, as you noted below. One trick I've used in the past when I got really desperate was to write a quick console app that used the same code that my Windows Phone app was executing. Then I was able to successfully intercept the traffic. It turned out that my request being properly formatted.