I've been out of town for the past 6 weeks, but have tested almost all my current and older GPS devices and they are fine (including the old etrex H - the "yellow" etrex).
As Orion mentioned, the error change does not necessarily have to occur on the rollover day itself - being due to the 10 bit week counter (1024 week limit). The date error may occur from the date stamped on the last firmware release or what ever date the GPS device sets as its "factory start date".
On my sisters old automotive Garmin Nuvi 500 which she still uses (I reckon this is about 10 years old or maybe a bit younger), it now consistently states the wrong date, starting from around December 2018. Eg. Her GPS stated 17 May 1999 when it was 31 December 2018. This happens to be 7168 days difference, or 1024 weeks.
Garmin have stated that the Nuvi 500 is no longer supported, so it seems unlikely that an updated firmware would be released for it.
Of note, the GPS on that Nuvi 500 still functions normally - the time is correct, and the GPS positioning is as accurate as it was previously. The incorect date is the only error. For her it isn't much of an issue, but if you were to rely on the sunrise/sunset data from a device with an incorrect date, obviously this information would be incorrect. And if your GPS device did not have a way to manually set the date, your track logs will be 1024 week behind.
Orion wrote:There are other ways to handle the problem. It's possible that the current date is updated in nonvolatile memory in the GPS module. That way, as long as you use the chip once every 19 years, it won't ever rollover. But is that how the chips I have deal with it? I have no idea.
In the ongoing effort to modernise GPS, around 2014 some satellites started broadcasting a an additional 13 bit date signal (this allows 8192 weeks or about 157 years for ongoing date rollovers, compared with the 1024 week/19 year limit for curent 10 bit date signal). Of course, legacy GPS devices need to account for the new signal, and where possible this might be accounted in firmware software updates).
Disturbingly though, I read yesterday on twitter that some Boeing 787s in China were grounded as they exhibited GPS date rollover error in their nav systems
https://twitter.com/ChinaAvReview/statu ... 8919411712 Surprising for an aircraft model that is under 12 years old.