Multiple Application_Start events firing

Question

I am debugging an ASP.NET 2.0 application that is suffering from slow loading of the initial page.

Through adding logging, I've found that the Application_Start event fires twice on startup with a short delay between the two events. The Session_Start event also fires twice, with the same Session ID value.

e.g.

[Header]
2010-09-10 14:52:36.331 INFO  Web.Global.Application_Start          START
2010-09-10 14:52:37.409 INFO  Web.Global.Session_Start              Session.SessionID=xxqjvun2ce2yqsumq1hfoj45
[Header]
2010-09-10 14:53:10.028 INFO  Web.Global.Application_Start          START
2010-09-10 14:53:10.325 INFO  Web.Global.Session_Start              Session.SessionID=xxqjvun2ce2yqsumq1hfoj45

I am running this on my local machine, under IIS 5.1. The project also uses ASP.NET MVC and the aspx page URL being used is altered using routing, using the technique shown on Phil Haack's site.

Any suggestions about what could cause this?

Ampere

Is the application by any chance modifying the web.config file? – Sura

Do you have Application_End fired in between? Do you have any calls to "HttpRuntime.UnloadAppDomain" in your code? – Issuance

In my case it was Mc Afee Virus scan. I followed this guide to exclude folders support.microsoft.com/en-us/kb/3126034 – Phanerogam

Answer 1

We eventually realised that this was down to our IIS configuration.

Some time ago a decision was made to rename the virtual directory used for this website. This was done by adding a whole new virtual directory configuration, leaving the previous one in place. Essentially we had two virtual directories pointing at the same ASP.NET app!

The migration to the new virtual directory was never completed, so parts of the website still referenced the old one. Hence two Application_Start events...

The fix was to change to setup to the old virtual directory in IIS to be A redirection to a URL with the URL set to /NewVirtualDirectory$S$Q

Ampere

Answer 2

After spending 4 days, I have finally found the problem out! If you change any file in Bin directory, IIS resets your application and Application pool. For me, it was because of log.txt file that my program used to write in Bin directory. I changed the log file path and the problem has been vanished!

Turbinate

Answer 3

We had a similar situation happen only to discover that it was because we had done an assembly rename and had two copies of the same code referencing that assembly existed, versionA.dll and versionB.dll. So it was being called twice because of that!

Logarithm

Answer 4

In my experienced (after hours research and tons of coding) that comes from

undeleted SQLite.Interop.dll in x64 folder

I deleted by File Management from hosting panel instead of FTP (FileZilla) and Multiple Application_Start events firing gone :-) Root causes of problems was unstoppable Quartz.Net process that was connected to this dll.

Nkvd

After more years, I faced with same problem and searching in google and found this solution again and It's mine ;-) I hope this helps too :-) – Nkvd