REAPER crashes during a thumbnail scan

With 1.2.5, this page should no longer apply

From 1.2.5, thumbnail scans run in a separate helper outside REAPER on the Mac and on Windows, so a crashing plugin cannot take REAPER down. If the helper crashes or is killed, the scan resumes with no duplicates. See Auto thumbnail scanner. The rest of this page is about 1.2.4 and earlier, and about the rare case where REAPER itself still closes during a scan.

Symptom: REAPER closes unexpectedly while the auto thumbnail scanner is running.

Cause: the scanner briefly instantiates each plugin in your library to render a screenshot. A small number of third-party plugins are unstable enough to crash their host when loaded this way — this is a property of that plugin, not something VFxM’s scan process can prevent outright.

Recover without losing progress

1. Relaunch REAPER normally.
2. Reopen VFxM. It detects the interrupted scan and offers Resume Crashed Scan.
3. Accept it — the scan continues from where it stopped, and the plugin that caused the crash has already been blocklisted automatically so it won’t be tried again.

Update to 1.2.2 if a crash keeps repeating

Before 1.2.2 the blocklist was written to one location and read back from another, so Resume Crashed Scan could start a plugin that had already taken REAPER down — the same crash, twice. Both halves now use the same file and the resume behaves as described above. Your existing blocklist is carried over when you update; nothing needs rebuilding.

If it keeps happening

Open Plugin Manager → Stability & Blocklist to see exactly which plugin is blocklisted. See Stability and the blocklist for how to review, manually unblock, or clear it entirely.

Isolate a known-unstable plugin before a big scan

If you already know a specific plugin is unstable — an old or discontinued build, for instance — moving it out of your scanned plugin paths before a full-library scan avoids the crash entirely rather than recovering from it.

Your project file is not touched by a scan.