I can't take credit for this, but found it on a developer help site. Hopefully this will help anyone plagued by the miserable support code 86000209
-Tracy

BEGIN QUOTE:
I cannot tell you how thankful I am that you provided the information
you did about 86000209. I upgraded to WM5.0 recently and upon
installation have continually received the exceptionally frustrating
86000209 error. I actually had tried deselecting email sync using
ActiveSync/Tools/Options on the desktop, syncing, and then reselecting
email sync, but to no avail. However, when I read the information you
provided the thought occurred to me that delesecting email sync using
the *DEVICE* ActiveSync program should be tried. That WORKED!!! So, I
just want to emphasize that for me it was important to deselect E-mail
on the device.


Here's the procedure that worked for me...


Upon receiving the 86000209 error:

- Disconnect handheld device from desktop

- Launch ActiveSync on the handheld device

- On handheld ActiveSync, select... Menu / Options

- Remove checkmark for E-mail

- ActiveSync informs that it will remove all email from the device
(this is probably why the procedure must be done on the device - in
order to remove the bad data)

- Connect handheld device to desktop

- Sync

- Once Sync is performed, and while handheld remains connected to
desktop, on the Desktop ActiveSync, select... Tools / Options

- Select E-mail, and save (note that there is not an option to select
folders yet - this comes later)

- Save the settings and by doing so Sync occurs again - this time
syncing your "inbox" (other folders will not be synced yet)

- Once Sync has completed, then you can go in once more to the
desktop ActiveSync... Tools / Options ... and select the folders and
other settings you want to use

- Save the settings and that will initiate Sync once more, this time
syncing all of the folders that you selected in the previous step

- DONE, and SUCCESS!!! No more 8000209 message!

I was sure I was going to have to reformat, and none of the information
I found searching helped, but the above procedure solved the issue.

Sincerely,
Bob

END QUOTE