Cannot read configuration file because it exceeds the maximum file size

Question

Is there a size limit for the iis web.config file?

I got this error when I had many redirect rules in web.config, If I remove these rules it will work normal.

Answer 1

@55 21

The default maximum limit is 250 KB. You can change this value by editing the registry key below (Reference). Make sure to restart the server after this change.

HKLM\SOFTWARE\Microsoft\InetStp\Configuration\MaxWebConfigFileSizeInKB

If you have hundreds of URL Rewrite rules, you can create rewrite maps and store them in a separate file.

Let’s say you have a rewrite map like the one below. Save it in a file called rewritemaps.config.

<rewriteMaps>
  <rewriteMap name="Redirects">
    <add key="/fromthisURL" value="/tothisURL" />
    <add key="/fromthisURL2" value="/tothisURL2" />
  </rewriteMap>
</rewriteMaps>

Then refer it from your web.config file:

<configuration>
<system.webServer>
  <rewrite>
    <rewriteMaps configSource="rewritemaps.config"><rewriteMaps>
      <rule name="Redirect rule">
         ...
      </rule>
  </rewrite>
</system.webServer>
</configuration>

You can store rewrite rules themselves in a separate file as well:

<rules configSource="rewriteRules.config" />

Reference documents: Web.config file maximum size and count

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