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:IIS6 access website prompt "503" error

Last Updated:Dec 24, 2020

Problem description

Website access using IIS6 service prompts "503" error.


The dll file cannot be loaded after the security dog is unloaded.


Alibaba Cloud reminds you that:

  • Before you perform operations that may cause risks, such as modifying instance configurations or data, we recommend that you check the disaster recovery and fault tolerance capabilities of the instances to ensure data security.
  • You can modify the configurations and data of instances including but not limited to Elastic Compute Service (ECS) and Relational Database Service (RDS) instances. Before the modification, we recommend that you create snapshots or enable RDS log backup.
  • If you have authorized or submitted sensitive information such as the logon account and password in the Alibaba Cloud Management Console, we recommend that you modify such information in a timely manner.

Please delete the contents of the filter attribute about security dog in the ISAPI filter.


  • Elastic Compute Service
  • Simple Application Server