Wordfast Pro being blocked or slowed down by anti-virus

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WFP Java crash report
Anti-virus (AV) software can prevent Wordfast Pro (WFP) in Windows from working properly.

The Problem

AVs usually block or quarantine the javaw.exe file inside the Wordfast program folder. When this happens, Wordfast fails to open; when you try launching it, the splash screen saying “Loading window content” usually shows but nothing else happens. When you end the process in the task manager, there's usually a long error message that starts with “Java was started but returned exit code=1”.

AVs can block other files or processes, too. We have seen cases where the user was unable to import package (GLP) files or add and use TMs in Wordfast (they kept disconnecting as inaccessible).

AVs regularly update their virus definitions and may use heuristic techniques. This means they can start blocking WFP all of a sudden after a silent virus-definitions update. Some AVs tell the user they blocked or quarantined a file or a process but some don't. So from the user's perspective, the inability to open Wordfast or use some of its features may come out of the blue.

We have seen troubles with Avast, AVG, F-Secure, Kaspersky, and McAfee. But it seems any AV can detect a Wordfast-related file or process as a “false positive”[1] and block or quarantine it. Fortunately, we have not seen problems related to Windows Security/Windows Defender.

Suggested solutions

When an AV is suspected of blocking Wordfast, it's a good idea to update its virus definitions first because the inaccuracy in the definitions may have been fixed already. AV producers strive to make sure their virus definitions detect viruses, including the latest ones; at the same time, they do their best not to detect “false positives” and block legitimate software.

The setting in F-Secure
We have seen a few cases where the user uninstalled the AV, which solved the problem. But most AVs let users mark programs as trusted and/or set exceptions/exclusions from real-time scans. The solution is to mark Wordfast as a trusted program or, most frequently, to exclude the Wordfast program folder (C:\Program Files\Wordfast Pro) and/or the folder(s) where your TMs, projects, or other Wordfast files reside from the AV real-time scanning.

Important: after setting up your AV to tolerate WFP, you may need to reinstall WFP in order to restore any previously quarantined or deleted Wordfast files (unless you can restore them from the AV's quarantine zone).

Here are some useful links:

Instructions for other AVs can be found on the web.

AV slowing down WFP

Even if your AV isn't blocking Wordfast, it can slow it down. If Wordfast feels slow, this can be attributable to your AV scanning WFP program files or your TMs and glossaries again and again as WFP reads from and writes to your TMs and glossaries. So it makes sense to set exceptions/exclusions in your AV (even Windows Security) to prevent it from checking your TMs and other Wordfast files all the time. It might be worth trying to exclude these folders from your AV's real-time scanning:

  • the Wordfast program folder in C:\Program Files\Wordfast Pro,
  • the Wordfast translation editor user folder in C:\Users\YOUR-USER-NAME\.gs4tr.editor, and
  • the folder(s) where your TMs and glossaries are stored.


  1. See the Wikipedia article about False positives and false negatives