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FEFLOW meshing error on Azure VM

Daniel Brox 20 Reputation points
2026-03-26T19:27:46.6533333+00:00

I downloaded FEFLOW11 on an Azure VM tech_support.jpg. When I run FEFLOW, I can create a quadrilateral supermesh, but when I try to mesh the quadrilateral, I get an 'Unspecified Error' VM_FEFLOW_Mesh_Error.jpg. As far as I know, no such error occurs when not using an Azure VM. Please advise on how to proceed, since this error currently prevents basic usage of FEFLOW11 demo and FEFLOW11 PAYG.

Windows for business | Windows Server | User experience | Remote desktop services and terminal services
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  1. Domic Vo 18,955 Reputation points Independent Advisor
    2026-03-27T18:17:30.67+00:00

    Hello,

    The “unspecified error” you are seeing when attempting to mesh a quadrilateral in FEFLOW 11 on an Azure VM is not a generic application bug but almost certainly tied to the virtualization environment. FEFLOW’s meshing routines rely heavily on low‑level numerical libraries and graphics acceleration. On a local workstation these libraries can access hardware resources directly, but inside an Azure VM you are limited to emulated graphics and constrained OpenGL support. That mismatch often manifests as vague errors during mesh generation, because the solver cannot allocate or initialize the required resources.

    The first step is to confirm whether the VM has GPU acceleration enabled. Standard Azure VMs without GPU support expose only software rendering, which is insufficient for FEFLOW’s meshing engine. You should provision an NV‑series or NC‑series VM with NVIDIA GPU passthrough, install the Azure‑certified NVIDIA drivers, and then re‑run the meshing operation. If you remain on a CPU‑only VM, the error will persist.

    If you already have GPU support, check that the Microsoft Remote Desktop session is not forcing GDI rendering. FEFLOW requires proper OpenGL context, and RDP sessions without GPU redirection will fail. In that case, you can test by connecting via Azure Bastion or enabling GPU acceleration for RDP.

    Finally, verify that the VM has sufficient memory and swap space. Meshing large quadrilaterals can consume several gigabytes of RAM, and Azure VMs with limited memory allocations may throw “unspecified error” when the allocation fails.

    In short, the issue is environmental: FEFLOW meshing requires GPU/OpenGL resources that are not available on a standard Azure VM. The remediation is to move the workload to a GPU‑enabled VM size, install the correct drivers, and ensure the session uses GPU rendering. That will align the Azure environment with the requirements of FEFLOW 11 and eliminate the error.

    I hope you've found something useful here. If it helps you get more insight into the issue, it's appreciated to accept the answer. Should you have more questions, feel free to leave a message. Have a nice day!

    Domic Vo.

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  1. Jilakara Hemalatha 11,515 Reputation points Microsoft External Staff Moderator
    2026-03-27T17:02:21.21+00:00

    Thank you for sharing the screenshots.

    From the details provided, we can confirm that the AMD Radeon Instinct MI25 GPU driver is installed correctly on the VM. However, the DirectX Diagnostic Tool shows that the system is currently using “Microsoft Hyper-V Video” as the active display instead of the AMD GPU. This indicates that the session is falling back to software-based rendering, which does not support the OpenGL features required by FEFLOW, leading to the meshing error.

    This behavior is commonly observed when connecting via standard RDP, as GPU acceleration is not enabled by default on Azure NVv4 VMs.

    To address this, please try the following:

    • Enable the Group Policy “Use hardware graphics adapters for all Remote Desktop Services sessions” on the VM: Computer Configuration → Administrative Templates → Windows Components → Remote Desktop Services → Remote Desktop Session Host → Remote Session Environment
    • Ensure that the correct AMD MxGPU (SR-IOV) guest driver for NVv4 series is installed as per: https://learn.microsoft.com/en-us/azure/virtual-machines/windows/n-series-amd-driver-setup
    • If the issue persists, consider using a GPU-aware remote access method such as Azure Bastion (native client) or NICE DCV, which better supports GPU acceleration and OpenGL workloads.

    Once the GPU is actively used for rendering instead of the Hyper-V display adapter, the OpenGL limitation should be resolved and FEFLOW meshing is expected to work normally.

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  2. Jilakara Hemalatha 11,515 Reputation points Microsoft External Staff Moderator
    2026-03-26T22:51:32.2133333+00:00

    Hello Daniel,

    Thank you for reaching out.

    From your description and the screenshots, the issue you’re encountering while using FEFLOW 11 on your Microsoft Azure Virtual Machine appears to be related to graphics/GPU configuration rather than a problem with the application itself.

    We noticed the message “OpenGL shaders not supported (using fallback)” in the FEFLOW logs. This typically means the VM is not currently using proper GPU acceleration and is instead falling back to software-based rendering. Since FEFLOW relies on OpenGL capabilities for mesh generation, this limitation can lead to the “Unspecified error” you’re seeing during meshing.

    Although you are using a GPU-capable VM (Standard NV4as v4), Azure N-series VMs require the appropriate vendor GPU drivers to be installed inside the VM to fully enable GPU functionality. Without these drivers, the system defaults to a basic display adapter, which does not provide the required OpenGL support.

    To resolve this, we recommend installing the AMD GPU drivers for the NVv4 series and then verifying that the GPU is properly recognized in Device Manager (it should not show as “Microsoft Basic Display Adapter”). After installation and a restart, please launch FEFLOW again and check if the OpenGL warning is no longer present, then retry the mesh operation.

    Could you please refer below documentations:

    https://learn.microsoft.com/en-us/azure/virtual-machines/windows/n-series-driver-setup

    https://learn.microsoft.com/en-us/azure/virtual-machines/windows/n-series-amd-driver-setup

    https://learn.microsoft.com/en-us/windows-server/remote/remote-desktop-services/rds-graphics-virtualization

    These documents explain the requirement for GPU drivers on NV-series VMs and how graphics acceleration works over remote sessions.

    Once the drivers are installed and GPU acceleration is enabled, FEFLOW should be able to use full OpenGL capabilities, and the mesh generation is expected to work normally.

    Hope this helps! Please let me know if you have any queries.

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