Rating: ★☆☆☆☆ (0.5 stars for heart palpitations caused)
In the high-stakes world of injection molding simulation, where we predict the flow of plastic down to the the micron, there exists a single error code that holds a mythical, almost urban-legend status among engineers. It is the "Blue Screen of Death" for the polymer crowd. It is cryptic, stubborn, and notoriously final.
It is Error 99998: Exclusive.
If you are reading this review, you have likely just encountered it. You have likely just spent three hours setting up a complex overmolding study with reactive molding elements, hit "Analyze," and watched your hopes crumble in milliseconds. This review covers the user experience, the root causes, and the existential dread associated with the infamous 99998.
If quick fixes fail, systematically apply the following solutions.
When Moldflow crashes or is force-closed (Task Manager), it does not delete the temporary lock file. This file, typically named *.lck or a hidden system file within the study folder, tells Moldflow: "This study is in use." Even though no session is active, the lock persists, triggering Error 99998. autodesk moldflow error 99998 exclusive
Configure your antivirus to exclude:
C:\Program Files\Autodesk\Moldflow 2025)D:\MF_Projects)%TEMP%\Moldflow)After adding exclusions, reboot and test.
Depending on your Moldflow version (2018 to 2025), the error may appear as:
"Error 99998: Unable to open study exclusively. The study may be open in another session or you do not have write permissions."
Or:
"Failed to open project database exclusively (Error 99998). Another user may have the study open. Modify the study settings or contact your administrator."
Sometimes, the error appears silently in the solver log when launching an analysis:
Opening study: C:\MFProjects\MyProject\Study_001
Error 99998: Exclusive lock could not be obtained.
Analysis aborted.
The keyword "exclusive" is your clue. This is not a mesh quality issue or a material data error. It is an I/O and permission conflict.
The Autodesk Moldflow Error 99998 Exclusive is not a fatal flaw in the software; rather, it is a guardrail that prevents data corruption from simultaneous access. However, when that guardrail malfunctions due to stale locks, network hiccups, or permission issues, it brings productivity to a halt.
By systematically applying the fixes outlined in this article—from deleting hidden lock files to adjusting SMB settings and registry keys—you can resolve Error 99998 in minutes instead of hours. More importantly, by adopting local project workflows and proper antivirus exclusions, you can prevent the error from recurring. The Ghost in the Machine: A Review of
Remember: "Exclusive" in Moldflow means exactly that—your study expects undivided access. Give it that, and Error 99998 will become a distant memory.
About the Author: This guide is compiled from over a decade of injection molding simulation support data, community forums, and Autodesk knowledge base articles. Always test fixes in a non-production environment first.
Last updated: October 2025. Compatible with Autodesk Moldflow Insight 2023–2026.
If you have exhausted all the above fixes and still see Error 99998 Exclusive, gather the following for Autodesk Technical Support:
.out or .log) showing the error.Provide this data via the Autodesk Subscription Center. In rare cases, Autodesk may provide a hotfix or script to patch the project database. The entire Moldflow installation folder (e