Moates Ostrich 2.0 COM Port Fix: Resolving the Handle-Is-Invalid Crash in Crome
Breaking Down the Handle-Is-Invalid (Error 6) Crash
When Crome tries to open the COM port and gets error 6, it’s failing at the OS level before it ever talks to the Ostrich. The device showing up as COM5 in Device Manager is actually a good sign — it means the FTDI USB-to-serial driver is installed and working. The crash happens one layer deeper, when Crome asks Windows for a handle to that port and Windows refuses.
Two things cause this most often: the FTDI latency timer is set too high for Crome’s timing requirements, or something else has the port locked. A third possibility — the Ostrich getting stuck in a bad firmware state — is less common but real, and Moates has a specific utility for it.
Fix 1: Drop the FTDI Latency Timer to 1ms
The Ostrich 2.0 uses an FTDI USB-to-serial chip to bridge the USB connection to the serial protocol the ECU speaks. The FTDI driver ships with a latency timer defaulting to 16ms. For most applications that’s harmless. For Crome talking to Moates hardware, it isn’t. The Moates documentation specifically says to set this value to 1 and describes the speed improvement as dramatic.
Here’s how to do it:
- Open Device Manager (press Win+X and select Device Manager).
- Expand the Ports (COM & LPT) section.
- Right-click your Ostrich port — COM5 in this case — and choose Properties.
- Click the Port Settings tab, then click Advanced.
- Find the Latency Timer (msec) field and change the value from 16 to 1.
- Click OK, unplug the Ostrich, count to three, plug it back in.
Before retrying in Crome, kill it completely through Task Manager — a frozen Crome instance can still hold the port locked even when the window is unresponsive. Start completely fresh.
Fix 2: Keep the COM Port Number Below 9
COM5 is fine on its own. But if you ever land on a port above COM8 after swapping USB hubs or reinstalling drivers, Crome will crash or silently fail. Older Windows serial software uses a different code path for ports above 8, and Crome doesn’t handle it. Moates’ own troubleshooting documentation recommends staying on COM3 or COM4 specifically.
To reassign: Device Manager, right-click the port, Properties, Port Settings, Advanced, and pick a lower number from the COM Port Number dropdown. Anything not listed as in use will work.
Fix 3: Run the DORESET Utility
If the latency timer fix doesn’t resolve it, the Ostrich may be stuck in a bad state. This happens when the device gets interrupted mid-operation — a power cut, a bad USB drop, a forced restart. Moates provides a small utility called DORESET (the Demon-Ostrich Reset Utility) specifically for this. It resets the bank configuration to a known baseline for standard 28-pin EPROM use. This is what the community usually means by ‘factory reset.’
Download DORESET from the Moates support site, run it with the Ostrich connected, then unplug and replug. No hardware work involved — it’s a software-level config reset that takes about a minute.
Check Whether Another Process Has the Port Open
A previously crashed Crome instance, Arduino IDE, PuTTY, or any other serial tool can hold a COM port open invisibly. Even after a window closes, the underlying process sometimes keeps the handle alive. Task Manager doesn’t always surface these. A free Windows utility called CurrPorts from NirSoft shows exactly which process owns any given open COM port. Kill the culprit, then retry.
Why Switching to HTS Makes Sense
Honda Tuning Suite is free, actively maintained, and works with the same Moates hardware — Ostrich, HULOG, all of it. It supports OBD0, OBD1, and CANBUS platforms including D, B, F, and H series engines. The team behind it built eCtune first, so the interface will feel familiar. It also imports Crome maps directly, so nothing you’ve already built gets thrown away.
Crome hasn’t had a meaningful update in years. When something breaks, there’s no active support channel. HTS has an active Discord that actually responds. For OBD1 Honda tuning today, it’s the better tool to be on.
The USB Cable Is Still Worth Swapping
A marginal cable won’t always prevent the device from enumerating — it can still show up as COM5 — but it can introduce intermittent communication errors that look identical to driver or firmware problems. Swap in a short, known-good USB-A-to-mini-B cable before chasing anything more complicated. Thin-conductor cables are a genuine source of grief with USB-to-serial adapters and often get overlooked.
Sources
- support.moates.net
- support.moates.net
- shop.moates.net
- hondatuningsuite.com
- docs.openbci.com
- ftdichip.com
- d-series.org
- youtube.com