SQL Reporting Services Error – Maximum request length exceeded

This error appears in SQL Server Reporting Services (SSRS) when a report request — usually one returning a large dataset or embedding large images — exceeds the maximum request size IIS is configured to accept.

The Error

Error: There was an exception running the extensions specified in the config file. Maximum request length exceeded.

The Fix

Edit the web.config file for your Report Server, typically found at:

C:\Program Files\Microsoft SQL Server\MSSQL.<instance>\Reporting Services\ReportServer\web.config

Find the <httpRuntime> element (it will already contain an executionTimeout attribute) and add a maxRequestLength attribute, specified in kilobytes:

<httpRuntime executionTimeout="9000" maxRequestLength="500000" />

500000 KB is roughly 500MB — adjust to whatever ceiling is appropriate for your reports. Save the file, then restart IIS for the change to apply:

iisreset

Alternatively, restart just the Report Server service rather than resetting all of IIS if other sites are hosted on the same server.

A Second Setting You May Also Need

If the report request is still being rejected after raising maxRequestLength, check IIS’s own request filtering limit as well — it enforces a separate ceiling independently of ASP.NET’s setting. In the <system.webServer> section of the same web.config, add or adjust:

<security>
  <requestFiltering>
    <requestLimits maxAllowedContentLength="524288000" />
  </requestFiltering>
</security>

maxAllowedContentLength is specified in bytes rather than kilobytes (524288000 bytes is roughly the same 500MB ceiling as the example above), which is a common source of confusion since it’s set right next to a value using different units.

Setting an Appropriate Ceiling

Raising these limits indefinitely isn’t free — a much larger allowed request size also means a much larger worst-case memory and processing load on the Report Server if something genuinely oversized (or malformed) gets submitted. Set the ceiling to comfortably cover your largest legitimate reports rather than an arbitrarily huge number, and revisit it if your reporting needs grow rather than starting from an overly generous default.

Screenshot: SSRS Maximum Request Length Error