In our role as Outsourced Tech Support for web hosts, we manage both Windows and Linux servers of our customers. In Windows Virtuozzo servers, one of the common errors reported by Odin Plesk web owners is “HTTP/1.1 New Session Failed“.

All sites in the server would suddenly start showing this error, and refuse to load. Sometimes the error goes off all by itself, but often times it’ll lead to a VPS restart.

What is this error?

“HTTP/1.1 New Session Failed” is an error displayed by the IIS server when it is unable to create a new session, often because it doesn’t have enough available resources to create one.

A look at the Event Viewer will most probably show “Event ID 4830”, which denotes low available memory in the system. This situation arises due to any of the following:

1. Un-optimized code – Check for recent updates to the applications, and observe if the processes are taking far too much memory than before.

2. Improper memory allocation – Check if Private Memory Limit is set for applications. This should be a function of total available memory, the expected number of processes and the expected memory usage per process.

3. VPS is under-resourced – If the above points all look OK, the issue could be low memory allocation compared to actual usage. If the traffic has grown (as seen from web analyzers), and the VPS has not been upgraded since purchase, you can be reasonably certain that the memory allocation is insufficient.

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How to fix this error?

If the server is still accessible over Remote Desktop (RDP), a restart of the IIS server will fix the issue. If RDP does not work, you’ll need to restart the VPS. However, this only fixes the symptom.

Based on what you determine as the cause, you may need to optimize the website code, configure memory limits for applications, or increase the VPS memory allocation.

Memory errors are common in Windows Virtuozzo servers. Having a clear idea of the different possibilities helps you to quickly identify the issue and minimize downtime for customers.

Bobcares helps Odin Plesk quickly recover from a crash, and avoid such issues in future. If you’d like to know how to make your server infrastructure and technical support more efficient, we’d be happy to talk to you.

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