CST 'tbbmalloc_proxy' cannot replace memory allocation routines

CST 'tbbmalloc_proxy' cannot replace memory allocation routines

In CST Studio Suite, a user may see the following warning while running the simulation with F-Solver:

"`tbbmalloc_proxy` cannot replace memory allocation routines (status:-1):
Success: free (ucrtbase.dll), byte pattern: <C7442410000000008B4424 >
Fail: _msize (ucrtbase.dll), byte pattern: <E9ABFFFFFFCCCCCCCCCCCC >
The solver will continue with a reduced performance."

This warning is shown in those infrastructure which uses its OS version 24H2 (such as Windows 11 or Windows Server 2025 etc.). The users who are using some other version of Windows 11 such as 22H2 or 23H2 may not see this warning.

As this is just a warning, it does not mean that any error has occurred, and therefore the simulation will succeed providing all the desired results after completion of the simulation.



Reason for giving the warning about reduced performance with Windows 11 24H2 version:

The F-Solver in CST Studio Suite uses Intel's oneTBB allocator to bypass the Windows OS Allocator and replaces it with Intel's HPC allocator to improve the performance on high core count CPUs.

Since the allocator is tightly coupled to the internals of the Windows OS, incompatibilities may occur if a Windows OS is used which is newer than the known Windows OS versions of the given oneTBB version of Intel shipped with CST Studio Suite.

If such an incompatibility is encountered, this warning is shown. Furthermore, the F-Solver will fall back to the Windows OS allocator.

The Intel’s oneTBB version shipped with CST 2025 and older CST versions have such an incompatibility with Windows version 24H2, hence this warning is shown.

Reduction in performance:

Even though the warning suggests that, “the solver will continue with a reduced performance”, the performance will not be reduced in every scenario.

For example, if a user is using the F-Solver with General Purpose method, the reduction in performance might only be observed when a user is using a large number of cores (like 64+ cores) in their simulation. For a F-Solver with Domain Decomposition Method, the performance may get affected significantly E.g., 4 times the total time.

Solution from CST v2026:

CST v2026 uses the latest Intel’s oneTBB version available which does not have any incompatibility with 24H2.

In case, an incompatibility of Intel’s oneTBB with future Windows OS versions is encountered, the following improved message will be shown which replaces the previous warning.


    • Related Articles

    • CST stops at finalizing matrices

      When CST file location is on OneDrive, the file syncing may cause issue for CST to start the excitation processing when the model becomes big enough. The symptom is that CST seems to be stuck at finalizing matrices stage. Small classroom examples did ...

    • CST Studio Suite update manager Download of update failed. Please try again later. error

      CST Update Manager 2025 allows one to stay up to date with the latest and greatest features and bug fixes in new service packs. Note: make sure you exit out CST before performing the update. If you encounter the following error message. It means that ...

    • CST simulation using Performance cores vs. efficient cores in Intel Processors

      Intel's 12th generation processors introduced the concept of performance cores(heavy-duty work) and efficient cores(used for background tasks), aiming to get work done while minimizing energy consumption. For CST simulation however, this means the ...

    • DS License server validation error exit code 256

      Question: Why am I seeing "The DS license server specified is not valid." error during installation of my SIMULIA software? The following messages are displayed when I tried to run the installer after setting my DSLS license server which is verified ...