How to handle errors in my code

Hi Frank, 

Thank you for reaching out.

We have reviewed your query regarding scenarios related to loading invalid Excel files and handling errors during editing in the Blazor Spreadsheet. Please find the details below.

Handling invalid Excel files during loading:

These warning dialogs are shown for the following cases:

• Invalid or unsupported file formats: If the loaded file is not in a supported Excel format, the Spreadsheet identifies this and shows a warning message.
    
  

• Large Excel files: When the uploaded Excel file exceeds the default file size or data size limit it will throw the alert dialog below to skip the opening of larger size in spreadsheet. By clicking the Cancel button, it will skip the importing progress. If you click OK button, then spreadsheet again tries to load the file.

Error handling during editing operations:

In general, during normal editing operations, the Blazor Spreadsheet does not raise runtime errors. Editing actions such as updating cell values handled smoothly without throwing exceptions.

For formula-related scenarios, the component handles validations as follows:

• Circular reference: If a circular reference is detected in a formula, the Spreadsheet displays a warning dialog to notify the user about the issue. Please refer to the attached image showing the circular reference warning dialog.
    

• Invalid or improper formula: If a formula is entered incorrectly or contains an unrecognized name, the edited cell will display #NAME! as the result.

Additionally, for editing, the Spreadsheet provides built-in editing events such as CellEditing and CellSaved. Using the CellEditing event, you can validate the input and cancel the edit operation before the value is saved to the cell. This allows you to prevent invalid data from being committed. The CellSaved event can be used to track successful edits after the value is stored. Please refer the below editing event documentation.

Kindly review the details shared above. Additionally, please provide the following information from your end to help us validate the issue further:

• If you are encountering any other issues while loading an Excel file that do not fall under the scenarios mentioned above, please share the Excel file with us. This will help us analyze the file and assist you more effectively.
• If you are facing any issues while editing a cell, please share the exact issue scenario, along with the steps that lead to the problem.
• If possible, please share an Excel file that reproduces the issue during editing.

Please share the above requested details from your end. Based on that, we will validate and update you with further details.

Please feel free to reach out to us if you have any further questions or concerns.

Regards,

Adithyan.

Dear  Adithyan,
so there is no chance to implement my own error handling style, with my own error dialogs with information I want to provide for the users. That is a pity. Are these error messages available in all languages or how can I set a translation?

And you did not cover the scenario in which the error is not shown in a message box but as part of the web site. I have added a hardcopy of the szenario. 
I assume the folder or file is write protected but I am not sure because I do not see any error message. All I can say it happens when the spreadsheet first loads the data.

Kind regards 

Frank

Dear  Adithyan,
so there is no chance to implement my own error handling style, with my own error dialogs with information I want to provide for the users. That is a pity. Are these error messages available in all languages or how can I set a translation?

And you did not cover the scenario in which the error is not shown in a message box but as part of the web site. I have added a hardcopy of the szenario. 
I assume the folder or file is write protected but I am not sure because I do not see any error message. All I can say it happens when the spreadsheet first loads the data.

Kind regards 

Frank

Hi,
the explanation for localization is very good. Thank you for that.

I found out in which case I get the error  of which I put a hardcopy in my last reply.
If you try to open the file I attached you will get the respective error message. As you notice this is an empty file. 

It would be good if you could cathc the empty file error. But all in all I am fine with your answers.

Thank you very ymuch
Frank

Thank you for your update.

We’re glad to hear that the explanation regarding localization was helpful.

We would like to clarify that in your previous reply, only the error image was attached. We did not find any hardcopy (sample file or project) in either your current or previous updates. However, as you mentioned earlier that the file might be protected, we attempted to validate this scenario on our side by loading both a password‑encrypted file and an empty file.

During our testing, we loaded the password‑encrypted and empty files in a project with localization enabled for different cultures. The validation dialog appeared as expected, and after entering the correct password, the file loaded successfully in our Spreadsheet component.

For your reference, we have prepared a short video demonstrating this behavior and attached it below along with the tested file.

Encrypted File: Please refer to the attachment (Password: Hello)

Since we were unable to fully reproduce the exact behavior you are encountering, we kindly request that you share the sample file you are trying to load or a minimal project that reproduces the issue. This will help us analyze the problem more precisely and provide an appropriate solution as quick as possible.

Hi,
I attached the file that leads to this message. It is somehow corrupt because it has the size 0 

A sample is included in the attached Zip

Kind regards

Frank

Hi,
I attached the file that leads to this message. It is somehow corrupt because it has the size 0 

A sample is included in the attached Zip

Kind regards

Frank

sorry attachement didn't work first time

Hi Frank, 

Thank you for sharing the file with us.

We have validated the reported issue by opening the Excel file you provided and were able to reproduce the reproduce exception while loading into our Spreadsheet. During our investigation, we observed that the file has a size of 0 KB and is corrupted, which results in a ZIP-related exception when attempting to load it into the Blazor Spreadsheet component.

Based on our analysis, we will handle the file‑loading error as described below:

• When a ZIP‑related exception occurs (for example, when loading a corrupted or zero‑byte file), the Spreadsheet component will display a warning dialog indicating that the file is unsupported.
  
  

• For other types of exceptions, the Spreadsheet will display a warning dialog with the exact exception details, allowing users to view the cause of the issue.

With these improvements, the Spreadsheet component will no longer crash if a file fails to load. Instead, it will show the appropriate warning message and continue functioning with the currently loaded Spreadsheet. 

Please review the above shared details and let us know if you have any further questions or concerns.

Regards,

Adithyan

We are glad to announce that our weekly patch release (33.1.46) is rolled out and we have included the fix for the reported "Exception occurs when loading corrupted or unsupported Excel file in Blazor Spreadsheet" issue in this release. So, kindly upgrade your package version to the latest to avail of these changes (33.1.46).

Package Link: NuGet Gallery | Syncfusion.Blazor.Spreadsheet 33.1.46

For your reference, we have attached the video demonstration with the latest Nuget.

Video demonstration:

Issue Root Cause:

During Excel file loading, ZIP‑related and file‑corruption scenarios were not adequately handled, which could result in unhandled exceptions when attempting to load corrupted or invalid files. This has been addressed by adding proper exception handling for ZIP and file‑corruption cases, where the Spreadsheet now displays an “unsupported file” warning dialog. In addition, general exceptions that occur during file loading are also captured and shown in a warning dialog with detailed error information, helping users easily identify the cause of the issue.

Please review the above shared details and feel free to reach out to us if you have any further questions or concerns.

Regards,

Adithyan

Hi,

unfortunately I still the same behavior.


The Spreadsheet version is updated.

In your example you used the UI to open the file but I am using this code in this code in the Blazor component to open the file. The content is sent as part of a message. 

  private void OnOpenExcelFileMessage(object recipient, OpenExcelFileMessage Message)
  {
      Debug.WriteLine("Razor: OpenExcelFileMessage received");
      DataSourceBytes = Message.ExcelFileContent;
      Debug.WriteLine($"Razor {DataSourceBytes.Length}");
      _spreadsheetKey++; // Change key to force component recreation
      StateHasChanged();
      WeakReferenceMessenger.Default.Send(new BusyMessage(this, false));
  }

 In the MAUI part of the app I am using this code (shortened). The FilePicker is a component from the .net maui 

Microsoft.Maui.Storage

varcustomFileType = newFilePickerFileType(
 
         new Dictionary<DevicePlatform, IEnumerable<string>>
         {
                 { DevicePlatform.Android, new[] { "application/vnd.ms-excel", "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet" } }, // MIME type
                 { DevicePlatform.WinUI, new[] { ".xlsx", ".xls"} }, // file extension
         });
          PickOptions options = new()
          {
              PickerTitle = AppResource.MainPageOpenWorkbookTitle,
              FileTypes = customFileType,
          };
          var result = await FilePicker.Default.PickAsync(options);
          if (result != null)
          {
                  if (result.FileName.EndsWith("xlsx", StringComparison.OrdinalIgnoreCase))
                  {
                      using (var memoryStream = new MemoryStream())
                      {
                          var fs = await result.OpenReadAsync();
                          fs.CopyTo(memoryStream);
                          fs.Close();
                          var data = memoryStream.ToArray();
                          WeakReferenceMessenger.Default.Send(new OpenExcelFileMessage(this, data));

                      }

                   }
          }

Could you please double check the solution if the file is loaded like I did.

Kind regards

Frank

Hi,

unfortunately I still the same behavior.


The Spreadsheet version is updated.

In your example you used the UI to open the file but I am using this code in this code in the Blazor component to open the file. The content is sent as part of a message. 

  private void OnOpenExcelFileMessage(object recipient, OpenExcelFileMessage Message)
  {
      Debug.WriteLine("Razor: OpenExcelFileMessage received");
      DataSourceBytes = Message.ExcelFileContent;
      Debug.WriteLine($"Razor {DataSourceBytes.Length}");
      _spreadsheetKey++; // Change key to force component recreation
      StateHasChanged();
      WeakReferenceMessenger.Default.Send(new BusyMessage(this, false));
  }

 In the MAUI part of the app I am using this code (shortened). The FilePicker is a component from the .net maui 

Microsoft.Maui.Storage

varcustomFileType = newFilePickerFileType(
 
         new Dictionary<DevicePlatform, IEnumerable<string>>
         {
                 { DevicePlatform.Android, new[] { "application/vnd.ms-excel", "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet" } }, // MIME type
                 { DevicePlatform.WinUI, new[] { ".xlsx", ".xls"} }, // file extension
         });
          PickOptions options = new()
          {
              PickerTitle = AppResource.MainPageOpenWorkbookTitle,
              FileTypes = customFileType,
          };
          var result = await FilePicker.Default.PickAsync(options);
          if (result != null)
          {
                  if (result.FileName.EndsWith("xlsx", StringComparison.OrdinalIgnoreCase))
                  {
                      using (var memoryStream = new MemoryStream())
                      {
                          var fs = await result.OpenReadAsync();
                          fs.CopyTo(memoryStream);
                          fs.Close();
                          var data = memoryStream.ToArray();
                          WeakReferenceMessenger.Default.Send(new OpenExcelFileMessage(this, data));

                      }

                   }
          }

Could you please double check the solution if the file is loaded like I did.

Kind regards

Frank

·        Passing a corrupted or zero‑byte Excel file

·        Dynamically assigning it to DataSourceBytes

·        Forcing component re‑creation using _spreadsheetKey++

·        Corrupted or unsupported files are safely intercepted

·        The application does not crash

·        Users receive a meaningful error message
 

Hi Frank,

We are glad to announce that our Essential Studio® 2026 Volume 1 Service Pack 1 (SP) Release v33.2.3 is rolled out and is available for download under the following link.

Essential Studio® 2026 Volume 1... | Announcements Forums | Syncfusion

We have included the fix for the issue "Unhandled Exception When Dynamically Updating Blazor Spreadsheet Data Source with Corrupted or Zero‑Byte Excel" in this release. We recommend updating to the latest version (v33.2.3) to obtain the fix.

Feedback link: Unhandled Exception When Dynamically Updating Blazor Spreadsheet Data Source with Corrupted or Zero‑Byte Excel in Blazor | Feedback Portal

For your convenience, we have prepared a sample with latest package and attached below along with the video demonstration for reference

Sample: Please refer to the attachment.

Video demonstration: