Users may encounter the following legitimate problems:
| Symptom | Likely Cause | Recommended Action |
|---------|--------------|---------------------|
| fsmainui.exe crashes on open | Corrupted UI configuration or installation | Repair F-Secure installation via Programs & Features → Change → Repair |
| High CPU usage (sustained) | UI stuck trying to refresh status (e.g., database update hang) | Restart the F-Secure service or reboot |
| Multiple fsmainui.exe processes | Each open UI window spawns a process | Close extra windows; normal behavior |
| “Application Error” at shutdown | UI closing before dependent service stops | Ignore if occasional; update to latest product version |
| File not found / missing | Incomplete installation or malware removal | Reinstall F-Secure product |
| Attribute | Details |
|-----------|---------|
| Full Name | F-Secure Main UI executable |
| Typical Location | C:\Program Files (x86)\F-Secure\ or C:\Program Files\WithSecure\ (subfolder varies by product version) |
| Publisher | F-Secure Corporation (now WithSecure) |
| Digital Signature | Should be validly signed by “F-Secure Corporation” or “WithSecure” |
| Typical Size | 1–5 MB (varies by version) |
| File Description | “F-Secure Main UI” or “WithSecure Main UI” |
| Product Name | F-Secure / WithSecure Client Security, PSB, or SAFE | fsmainui.exe
If in doubt:
Cause: A corrupted DLL that F-Secure depends on, or a failed update. Users may encounter the following legitimate problems: |
Solutions:
Cause: Typically a corrupted F-Secure installation, damaged Windows system files, or a conflict with another application. Causes include: missing Visual C++ Redistributables
Solutions:
This error appears if the F-Secure service fails to launch the UI component. Causes include: missing Visual C++ Redistributables, a Windows update conflict, or a failed F-Secure update.
Even though the file is safe, users sometimes encounter errors. Here are the most frequent issues: