HTTP Error 503. The service is unavailable

Question

I'm struggling to setup the environment in IIS8, I searched a lot but couldn't find a right solution.

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I checked the error logs, but no idea.

C:\Windows\System32\LogFiles\HTTPERR

2013-10-09 09:28:39 192.168.43.205 60172 192.168.43.205 80 HTTP/1.1 GET / 503 2 AppOffline qa.hti.local

2013-10-09 09:28:39 192.168.43.205 60192 192.168.43.205 80 HTTP/1.1 GET /favicon.ico 503 2 AppOffline qa.hti.local

Then in Event Viewer:

WARNINGS:

A listener channel for protocol 'http' in worker process '11188' serving application pool 'qa.hti.local' reported a listener channel failure. The data field contains the error number.

A listener channel for protocol 'http' in worker process '7492' serving application pool 'qa.hti.local' reported a listener channel failure. The data field contains the error number.

A listener channel for protocol 'http' in worker process '9088' serving application pool 'qa.hti.local' reported a listener channel failure. The data field contains the error number.

A listener channel for protocol 'http' in worker process '9964' serving application pool 'qa.hti.local' reported a listener channel failure. The data field contains the error number.

A listener channel for protocol 'http' in worker process '7716' serving application pool 'qa.hti.local' reported a listener channel failure. The data field contains the error number.

I don't understand what the warning means.

ERROR: Application pool 'qa.hti.local' is being automatically disabled due to a series of failures in the process(es) serving that application pool.

Note: I learned that consecutive 5 failures leads to APP Pool crash, and this can increased. I also tried increasing this but no success.

Please share your thoughts.

Check this in [Server Fault](http://serverfault.com/) – Murali Murugesan Oct 09 '13 at 10:59 — Murali Murugesan, Oct 09 '13 at 10:59

score 6 · Answer 1 · answered Jan 23 '14 at 16:11

I came across this question as I was experiencing a similar issue and searching for a solution.

My problem specifically had to do with our IIS shared configuration. We had enabled a feature in IIS on one of the servers (Http Redirect) that was not installed on any of the others so the server 'features' were out of sync with all the servers.

I was able to resolve the issue by uninstalling the new addition on the first server so it was back to matching the others. An IIS reset later and the AppPools were no longer going down and all was back to normal.

So if you are using IIS Shared Configuration and the IIS is creating 'Service Unavailable' errors and the AppPools are going down, this can be a symptom of the system configuration being out of synch which is corrupting the shared configuration. Hopefully this post will help someone find the solution faster than I was able to.

We had the same issue when migrating from one server to another. The new server shut the AppPools down and displayed 503. Turns out it din't have Http Redirect unlike the original server. Installing the missing feature solved the problem. — kojo, Apr 25 '14 at 18:42
@kojo HttpRedirect is the exact feature we were missing as well. — Kelsey, Apr 28 '14 at 14:37
This solved my issue. I had ARR installed on the main IIS, and all the other instances did not have it. Installed, and everything went to working. THANK YOU!!! — CodingEE, May 29 '20 at 04:58

score 4 · Answer 2 · answered Jul 02 '15 at 11:30

I had a similar problem, and it was due to another error (2282 IIS-W3SVC-WP) that the pool stopped itself. My problem was that de module owssvr.dll could not be loaded due to a configuration problem. The solution for me was to set the setting "Enable 32-bit applications" from True to false.

I was deploying a solution on Sharepoint 2013 on a Windows Server 2012 with Visual studio 2013.

I know this was supposedly a very specific problem, but I want to help all those with the same problem.

score 1 · Answer 3 · answered Nov 10 '13 at 13:49

1

Propably you do not have the permissions to read the directory.

The directory (and the files) need to have read-access for either windows-group "USERS" or windows-grou "IIS_IUSRS" and also for your apppoolidentity.

answered Nov 10 '13 at 13:49

Chris Berlin

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score 1 · Answer 4 · answered Aug 22 '19 at 06:24

1

This occurred for me too on Windows 10 1803 after an update.

Earlier in the event log there were errors to do with missing DLLS, specifically iiswsock.dll and compstat.dll.

After turning on the following Windows features (under IIS > WWWServices > Performance Features and AppDev Features):

Dynamic and Static Content Compression, and
WebSocket Protocol Windows features

those errors disappeared after an IIS restart.

answered Aug 22 '19 at 06:24

sHr0oMaN

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After adding Static Content Compression it started working. No idea why dotnet 5 needs this feature. – Angel Yordanov Dec 08 '20 at 18:09

Zen · Answer 5 · 2021-01-19T10:34:23.027

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I reinstalled server and copied applicationHost.config to new server, but not installed corresponding modules, and got this error. I fixed that by check modules in IIS manager and ensure modules are installed.

Update: In Windows Logs-> Application, there're some info about which module is missing.

edited Jan 19 '21 at 10:34

answered Jan 19 '21 at 09:16

Zen

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Thanks for "Windows Logs" update. Access the log in the "Event Viewer" by doing this: Start > Administrative Tools > Event Viewer > Windows Logs > Applications. In my case, this provided the name of a missing ".dll". – IAM_AL_X Apr 23 '23 at 19:53

score 0 · Answer 6 · answered Apr 01 '14 at 22:33

0

503 2

Is that 2 the substatus code? If so, you might want to make sure your site is not being hit with excessively (5000+) # of requests.

http://support.microsoft.com/kb/943891

The data field contains the error number.

what's the error number?

answered Apr 01 '14 at 22:33

an phu

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1
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score 0 · Answer 7 · answered Nov 18 '14 at 22:59

This also can be caused by you're software vendor not realizing that they installed the 32bit version of the application pool apps on your 2008 R2 server. After a little troubleshooting my server because they wanted me to reinstall IIS i checked the windows app logs and emailed them the x86 architecture error for their app.

score 0 · Answer 8 · answered Sep 07 '15 at 18:44

This can occur if a piece of IIS is missing (e.g. one of the many IIS modules has not been installed on the new server).

The thing to do is to carefully compare the IIS config of the source and target, and add the missing pieces to the target.

In a recent IIS8.5->8.5 migration, I had this issue. Went through the whole stack. The last piece was that the Web Cert auth piece of IIS was missing.

To install:

powershell
import-module servermanager
add-windowsfeature Web-Cert-Auth

score 0 · Answer 9 · answered Nov 16 '21 at 19:01

In case this helps anyone else: We run multiple https sites on an IIS 10 server. One of the steps in configuring a new site is to give the new application pool permission to the system certificate. In the registry, under HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\SystemCertificates\MY, grant the application pool on the local machine full control. That fixed this issue for us.

score -1 · Answer 10 · answered Jul 06 '17 at 10:50

I had the same problem and solved it by adding the domain account the application pool was using as an identity to the local group of Administrators on a web server. Perhaps it would also do the trick to grant access to the application directory for the application pool identity account, as @Lisa-Berlin stated above.

HTTP Error 503. The service is unavailable

10 Answers10