Today I started receiving a 503 error "The service is unavailable." from a web app. The other web apps on the same (S1) service plan seem to be working fine, so I don't think this is a quota issue. The issue started after a simple stop / start of the app service this morning. I've tried searching for solutions but haven't found anything helpful. Can anyone shed some insight on why I may be receiving this error?
Turns out the problem comes from maxed out SNAT ports from a separate application within the same service plan.
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My azure web app service suddenly becomes unavailable for a few hours.
The app hosts .net core 3.1 web API.
All the requests are pending for a few minutes and then fail. Restarting the app doesn't help. Stopping and starting again too.
Applications insights don't show those failed requests.
Please help, the app serves a lot of users and requests!
I have run Availability and Performance diagnostics at the time of the crash:
Everything looks just fine except the failed requests.
As suggested earlier , you can debug why the web app went unavailable by running the availability & performance under Diagnose and solve problems in the portal.
You can also refer this Azure documentation to troubleshoot Troubleshoot HTTP errors of "502 bad gateway" and "503 service unavailable" in Azure App Service
if you are still not able to find any insights , why the webapp went unavailable you can open a discussion over Microsoft Q&A or please create a technical support ticker by following the link where technical support team would help you in troubleshooting the issue from platform end.
We have deployed in Azure Portal some app services under a free plan. The apps seem to be healthy and were working without problems until today. Suddenly all of them are returning an Error 503 "The service is unavailable.".
Under one of the services in Diagnose and fix problems in azure portal I checked CPU, Memory, Port usage and everything looks healthy.
Any ideas on how to fix the issue?
Could that be Microsoft maintenance and after some hours the sites are working normally again?
After 5 hours the services were up again. Probably it was a maintenance issue. So after no indication that my services have a problem, waiting some hours was the solution. Maybe this site that displays the azure status could be helpful for those that run into this problem.
Our website has been hosted on Azure for a few years. Tonight it is throwing 503 Service unavailable errors. I cannot even load a url to a .jpg file. I have restarted the app and still nothing loads from the website. I cannot buy Azure support because I have bought and cancelled Azure support in the past. We are a 3 person business and depend on our small website and it is down and I don't know what to do. None of the trace logs make any sense to me.
I think 503 could mean that you reached a quota and Azure now respond with a 503 for requests. So I would check the Quotas section within your App Service Plan.
Also check:
Troubleshoot HTTP errors of "502 bad gateway" and "503 service unavailable" in Azure App Service
There are several things you can do to help remedy the situation.
Restart the application (please indicate what it is that will help
us)
Restart the instance that the application is running on.
Restore from a previous working backup of the site.
You should also add more information to your post so we can help, like what application you are using e.g. Apache, Nginx ect.
I've also had a similar problem. I had two deployment slots and in the first slot (production) which I had the latest code and in the second slot, I've missed deploying the latest code and configured traffic as 60-40 which gave me hard time finding it.
Once I've set 100% to the production slot it started working.
Just thought to share this in case it could be useful if you come across the same stuff in the future.
For me it was "Path mappings" in "Configuration".
As soon as i added a new Azure Storage Mount, the application broke.
Setting my Storage account -> Networking, to "Enabled from all networks" fixed the issue.
For us it was a result of the remote debugger. Disabling remote debugger and restarting the app service fixed the 503 error. I think one dev was remote-debugging while another was deploying the app and that seems to have caused an issue under the hood of the app service that broke port binding (we were seeing a stack track in logs about failing to bind to port).
Seeing 502 error for the past 6 hours.
Tried restarting the server but it didn't do anything.
It is hosted on a VM (instead of being an Azure Web App).
Azure region: North Europe.
App Insights resource didn't report of any problem.
Website is written in mvc core.
What do I do to fix this?
If you have already tried the link suggested by DonNetMatt, then, here is what I would do.
You said you are hosting it in a VM. could you try redeploying the site to another server (web app or VM), and if possible another region. This should tell you if the issue is really with your web app or the server.
In all likelihood, the redeploy should load the site just fine, in which case contacting Azure support is the best way to solve this issue.
I doubt if the issue is on your code. With the error you are getting, its likely a server issue on Microsoft Azure side.
(Note : I am assuming when you say 'Website is writting in mvc core' you mean, website is written in mvc core. Or, is your website designed to write code as part of some automation thing, and generating MVC code?)
I have the strange problem, that began near one week ago. I have the site, hosted as a cloud app (a webrole with at least 2 instances running, auto scaling up to 4 max) in Azure. And from time to time when I open it I get 503 Service Unavailable error. But if I will refresh the page, site will open without any errors. QA site at the same time works without any problems. May you know why it's going on? Thanks!
503s in Azure App Services are one of these three:
You've reached the quota for the underlying app service plan (obviously doesn't apply to a premium plan)
You're using deployment slots and hitting a slot that is missing code (if the slots are 50%/50% or something like that it would explain why the 503 is intermittent)
Remote Debugger is preventing port binding of the application. Try disabling Remote Debugging and restarting the app service.