Excel 2021 LTSC Crashing With Conditional Formatting And Office.js Add-ins A Troubleshooting Guide

Introduction

Excel conditional formatting and custom functions are powerful tools, enhancing spreadsheet functionality. However, the interaction between these features and Office.js add-ins can sometimes lead to unexpected issues. This article delves into a specific problem encountered by users of Excel LTSC 2021, where the presence of an Office.js add-in, combined with complex conditional formatting rules and custom functions, results in crashes. Understanding the root cause and potential solutions is crucial for those relying on Excel for critical reporting and data analysis. If you're experiencing similar issues, this guide aims to provide clarity and possible workarounds to ensure your Excel experience remains smooth and efficient. We will explore the problem in detail, examine the diagnostic analysis, and discuss potential implications and solutions.

The Problem: Excel Crashes with Conditional Formatting, Custom Functions, and Office.js

Many users are leveraging Excel's capabilities with extensive reports that utilize a significant number of conditional formatting rules and custom functions. These reports, varying in size from a few sheets to over ten, and incorporating numerous custom functions, have encountered a critical issue: Excel crashes when closing the files. The core issue arises when these reports are used in conjunction with Office.js add-ins. The problem manifests as a gradual and relentless increase in memory usage upon closing the file, eventually consuming all available memory and leading to an Excel crash. Surprisingly, this issue doesn't require any interaction with the add-in itself or any active use of Excel functions; simply opening and closing the workbook is sufficient to trigger the crash. Removing the Office.js add-in resolves the problem, highlighting a conflict between the add-in and Excel's handling of conditional formatting and custom functions. This situation is particularly challenging for users relying on these reports for essential tasks, as unexpected crashes can disrupt workflows and potentially lead to data loss. Identifying the specific conditions that cause these crashes is crucial for developing effective solutions and preventing future occurrences. The key concern is the compatibility between Office.js add-ins and complex Excel workbooks, especially in the LTSC 2021 version.

Environment and Symptoms

To fully understand the scope of this problem, let's examine the environment in which it occurs and the symptoms users experience. This issue primarily affects users of Excel 2021 LTSC on Windows desktop environments. Specifically, it has been observed in version 2108, Build 14332.2100. The operating system plays a significant role, as the interaction between Excel and the underlying system resources can influence the stability of the application. The primary symptom is a dramatic increase in memory usage when closing workbooks containing numerous conditional formatting rules and custom functions, especially when an Office.js add-in is active. This memory consumption continues until all available memory is exhausted, leading to a complete crash of Excel. This behavior differs from typical Excel usage, where memory is released after closing a file. The fact that the crash occurs even without active interaction with the workbook or the add-in indicates a background process or conflict is at play. The expected behavior, of course, is normal memory usage and a clean exit from Excel without any crashes. The contrast between the current behavior and expected behavior underscores the severity of the issue. This problem is particularly acute because it can occur without any specific user action, making it difficult to predict and prevent. The memory leak issue combined with the ultimate crash disrupts workflow and leads to potential data loss.

Steps to Reproduce the Excel Crash

Reproducing the issue is vital for understanding and resolving it. Here's a step-by-step guide to replicate the Excel crash: 1. Open an Excel workbook containing a substantial number of conditional formatting rules and custom functions. 2. Ensure that an Office.js add-in is present and active in Excel. 3. Simply close the workbook. Observe Excel's behavior. 4. You'll notice that Excel becomes unresponsive. Over time, the system's memory consumption increases dramatically. 5. Eventually, Excel will crash due to memory exhaustion. This sequence of actions reliably triggers the crash, confirming the interaction between the complex workbook, the Office.js add-in, and Excel's memory management. The simplicity of the steps highlights the underlying issue: a fundamental conflict rather than a complex operational sequence. This ease of reproduction is both a benefit and a concern. It allows developers and users to quickly verify the problem and test potential solutions, but it also means the crash can occur frequently and unexpectedly in real-world scenarios. Understanding these steps helps in creating targeted fixes and strategies to mitigate the problem. A critical aspect is the combined presence of the conditional formatting, custom functions, and the Office.js add-in.

Impact and Context of the Issue

The impact of this Excel crash issue extends beyond mere inconvenience. It disrupts critical workflows and can potentially lead to significant data loss. For users relying on Excel for reporting, analysis, and other essential tasks, unexpected crashes can result in lost progress and wasted time. Imagine spending hours working on a complex report, only to have Excel crash just as you're about to save it. This scenario underscores the importance of stability in a business-critical application. The fact that this issue specifically affects Excel LTSC 2021 presents a unique challenge. Many organizations choose LTSC versions for their stability and long-term support, avoiding the frequent feature updates of other Office versions. However, this also means that fixes and improvements may not be available as quickly as in other channels. The customer experiencing this issue cannot upgrade to Office 2024 LTSC in the immediate future, making a solution within the current environment essential. This situation highlights the need for workarounds or patches that can address the crash without requiring a full version upgrade. The inability to upgrade places a greater emphasis on identifying the specific cause of the crash and finding a targeted solution. The context of this issue emphasizes the criticality of stability in enterprise environments, where Excel is often a core tool for data management and reporting.

Debug Diagnostics and Log Analysis

To effectively address the Excel crash, a thorough analysis of debug diagnostics and log files is essential. DebugDiag was used to capture detailed information about Excel's behavior leading up to the crash. The analysis reveals a complex sequence of events, involving various modules and threads within Excel. On July 24, 2025, at 9:30:50 AM, DebugDiag launched Excel (PID 10736) under the CrashRule_Process_excel script. Over the next few minutes, Excel loaded numerous system and Office modules and spawned many worker threads. During this period, the process experienced multiple first-chance exceptions (handled by DebugDiag) before ultimately terminating with an unhandled error. Key modules involved include EXCEL.EXE, various VCRUNTIME140/MSVCP140 runtimes, and Office UI libraries (mso20win32client.dll, mso30win32client.dll, mso40uiwin32client.dll, etc.). Notably, antivirus hooks from McAfee (MfeAmsiProvider.dll, mfehcinj.dll) were also loaded early in the process. The analysis identified a series of exceptions occurring in the lead-up to the crash: licensing failures (0xC004F012), web authentication errors (0x40080201), C++ exceptions within Office UI code (0xE06D7363), RPC server unavailable errors (0x000006BA), an access violation (0xC0000005), and a final unhandled CRT parameter error (0xC000041D). This cascade of errors points to a deep-seated problem within Excel's interaction with system resources and add-ins. Understanding the timeline and types of exceptions is crucial for pinpointing the root cause and developing a targeted fix.

Key Findings from Exception Timeline

The timeline of exceptions reveals critical insights into the Excel crash. The initial exceptions are related to licensing failures (0xC004F012) stemming from the Microsoft Software Protection Platform (sppc.dll). These indicate issues with RPC calls during SLGetPolicyInformation, suggesting a misconfigured or unreachable licensing service. Although these are first-chance exceptions, meaning they were initially handled, their prevalence indicates an underlying problem. Early COM exceptions (0x40080201) in Windows_Web and Windows_Security_Authentication_Web_Core suggest failures in retrieving identity-provider cookies, possibly due to missing registry entries or blocked network endpoints for the Web Auth API. These errors may be related to authentication processes triggered by the Office.js add-in. A significant number of C++ exceptions (0xE06D7363) occur within Excel's UI code (mso30win32client.dll, mso40uiwin32client.dll), pointing to invalid state or corrupted parameters in Office's callback routines. These exceptions escalate to an access violation (0xC0000005) and a final unhandled CRT parameter check (0xC000041D), which forces the process to terminate. The presence of RPC server unavailable errors (0x000006BA) during access to DAV (WebDav) or network shares suggests delays or failures in file-system operations within Excel, potentially exacerbated by the add-in's activity. The progression of these exceptions paints a picture of a system under stress, where initial licensing and authentication issues lead to more severe problems in Excel's core functionality. This timeline is invaluable in focusing troubleshooting efforts on the most critical areas.

Root Cause Analysis

Based on the debug diagnostics and log analysis, a comprehensive root cause analysis can be formulated. The Excel crash appears to be triggered by a combination of factors, with the Office.js add-in playing a central role in exacerbating existing issues. 1. Licensing Failures: The numerous licensing failures (0xC004F012) suggest a problem with Excel's activation or licensing service connectivity. This could be due to network issues, misconfigured settings, or problems with the Software Protection Platform. 2. Web Authentication Issues: The web authentication errors (0x40080201) indicate potential problems with the Office.js add-in's authentication process. This might involve missing or incorrect credentials, blocked network endpoints, or conflicts with other authentication mechanisms. 3. C++ Exceptions and Access Violations: The cascade of C++ exceptions (0xE06D7363) and the final access violation (0xC0000005) point to memory corruption or invalid state within Excel's UI code. This is likely triggered by the interaction between the complex conditional formatting, custom functions, and the Office.js add-in. 4. RPC Server Unavailable Errors: The RPC server unavailable errors (0x000006BA) suggest delays or failures in file-system operations, potentially related to network connectivity or access permissions. These issues may be amplified by the add-in's attempts to access resources or interact with Excel's file handling processes. The overall picture is one of a system struggling to manage complex operations while also dealing with authentication and licensing challenges. The Office.js add-in appears to act as a catalyst, pushing Excel beyond its stability threshold when handling large workbooks with extensive conditional formatting and custom functions.

Potential Solutions and Workarounds

Addressing the Excel crash requires a multifaceted approach, targeting the identified root causes. Here are some potential solutions and workarounds: 1. Investigate Licensing Issues: Verify that Excel is properly activated and licensed. Check network connectivity to ensure the licensing service is reachable. Review firewall settings to ensure no necessary endpoints are blocked. Consider running the Office Activation Troubleshooter to identify and fix licensing problems. 2. Troubleshoot Web Authentication: Examine the Office.js add-in's authentication settings. Ensure that the necessary credentials are correctly configured. Check for any network issues that might be preventing authentication. Review registry settings related to Web Authentication API. 3. Simplify Conditional Formatting and Custom Functions: Reduce the complexity of conditional formatting rules and custom functions within the workbook. Break down complex formulas into simpler ones. Consider using Excel's built-in functions where possible, rather than custom functions. 4. Disable the Office.js Add-in: As a temporary workaround, disable the Office.js add-in to see if the crash is resolved. If the crash no longer occurs, this confirms the add-in's involvement and allows for more focused troubleshooting. 5. Update Office 2021 LTSC: Ensure that Excel 2021 LTSC is updated with the latest patches and fixes. Microsoft may have released updates that address similar issues. 6. Check Antivirus Interference: Temporarily disable antivirus software to see if it is interfering with Excel's operation. Add Excel to the antivirus software's exception list if necessary. 7. Review Memory Usage: Monitor Excel's memory usage while working with large workbooks. Close unnecessary applications to free up system resources. Increase virtual memory if necessary. These solutions are designed to address different aspects of the problem, from licensing and authentication to workbook complexity and system resource management. Implementing these steps can help mitigate the Excel crash and improve overall stability.

Conclusion

The Excel crash experienced by users of Excel LTSC 2021, particularly when using complex workbooks with conditional formatting, custom functions, and Office.js add-ins, is a significant issue that requires careful attention. The root cause analysis reveals a combination of licensing problems, web authentication errors, and memory corruption within Excel's UI code, exacerbated by the presence of the Office.js add-in. Addressing this issue involves a systematic approach, including investigating licensing and authentication, simplifying workbook complexity, updating Office, and checking for antivirus interference. While a permanent fix may require updates from Microsoft, the workarounds discussed can help mitigate the problem in the meantime. By understanding the underlying causes and implementing these solutions, users can minimize the risk of crashes and maintain a stable and productive Excel environment. It is essential to continue monitoring for updates and engaging with the Microsoft community to share experiences and solutions. This collaborative approach will contribute to resolving this issue and ensuring the reliability of Excel for critical business operations.