One known cause of this error is ASP.NET security limitations on the number of form keys, query string parameters, and uploaded files in a single request. These limitations are enforced by default as part of Microsoft Security Update MS11-100 to help prevent Denial of Service (DoS) attacks.

• The setting aspnet:MaxHttpCollectionKeys determines the maximum number of form fields that can be processed in a request.
• The default limit is 9999. If the Web Data Entry page sample exceeds this limit, an error may occur.

Windows OS. 

1. Increase the aspnet:MaxHttpCollectionKeys Limit

• Open IIS Manager
• Navigate to Data Entry > Application Settings
• Locate and increase the value of aspnet:MaxHttpCollectionKeys" beyond 9999 (e.g., 12,000 based on metadata needs)

- Alternatively, update the web.config file by adding the following entry inside the <appSettings> section:

  <appSettings>
      <add key="aspnet:MaxHttpCollectionKeys" value="12000"/>
  </appSettings>

2. Restart IIS

• After updating the setting, restart IIS to apply the changes:
• Open Command Prompt as Administrator
• Run the command:
  IIS RESET

3. Validate the Fix

• Reattempt the data entry operation in Statistica Web Data Entry
• If the issue persists, incrementally increase the limit beyond 12,000 based on additional metadata or hidden fields being submitted.

Alternative Solution:

If increasing the limit is not preferred, consider splitting the sample data before submission to stay within the allowed limit.

Note:

Security Consideration: Increasing aspnet:MaxHttpCollectionKeys beyond 9999 increases exposure to DoS attacks. It is recommended to adjust this setting only based on actual business needs and avoid setting it excessively high.

While using Statistica Web Data entry customers may encounter an error when attempting to edit samples containing a large number of entries. The error message displayed is:

"An unexpected error has occurred in STATISTICA Web Data Entry. An event log message with details of the error has been logged on the server."

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