C1MultiDocument IndexOutOfRangeException error on WinForms .Net 8+

C1MultiDocument IndexOutOfRangeException error on WinForms .Net 8+

Posted by: hrvoje.zirdum on 11 March 2026, 9:03 am EST

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  hrvoje.zirdum

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  Posted 11 March 2026, 9:03 am EST - Updated 11 March 2026, 9:08 am EST

  Hi all
  
  After I upgraded the C# WinForms project from .Net Framework 4.8.1 to .Net 8, then 9 and 10, an error started appearing when using C1MultiDocument. In my project, the error “IndexOutOfRangeException: Index was outside the bounds of the array” occurs. in this part of the code this.c1PrintPreviewControl1.Document = this.multiDoc;
  
  Attached is the same error that appears on your MultiDocumentFilesprint example that comes with the Mescius controls installation.

  I am using the latest version of Mescius WinForms controls with Visual Studio 2022 and 2026.
  
  Can you help me solve this problem?

  Regards,
  
  Hrvoje

  

  1202×670 84.4 KB

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  uttkarsh.matiyal

  

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  Posted 12 March 2026, 8:49 am EST

  Hello Hrvoje,

  We were able to reproduce this behavior on our end using the MultiDocumentFilesPrint sample you mentioned.
  
  We have escalated the behavior to the development team and will get back once we have more information. [Internal Tracking ID: C1WIN-35103]

  Regards,
  
  Uttkarsh.

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  hrvoje.zirdum

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  Posted 31 March 2026, 2:06 pm EST

  Same error happens with framework 4.8.1 with all versions above 740.
  
  I cannot build and make new app version now.
  
  When do you plan to make a fix or something,

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  uttkarsh.matiyal

  

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  Posted 31 March 2026, 11:56 pm EST

  Hello Hrvoje,

  The issue has been resolved internally and will be included in the 2026 v1 release or a subsequent hotfix. We’ll update you once the fix becomes available.

  Regards,
  
  Uttkarsh.