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Solution ID : SO14352

Last Modified : 05/02/2018

Error occurs when submitting renewal CSR with Microsoft IIS 7 or 8: "Unable to decode CSR data. Key size may be too large"

Problem

This document was created to assist with the resolution of an error in IIS 7 or IIS 8. If this document can not be used within the environment, GeoTrust recommends contacting an organization that supports IIS 7 or IIS 8.

Error Message

When submitting a CSR to renew a certificate IIS 7 or 8, this error message occurs:

Unable to decode CSR data. Key size may be too large

Solution

If the CSR was generated using the Replace or Renew function in IIS, this is a known Microsoft issue.  For more information, please see the following Microsoft Knowledge Base Article.
Currently, the only way to resolve this issue is to select the option to Create Certificate Request as opposed to Renew. To generate a valid CSR, use the steps in this link.