sync error - illegal start of token

[danbecker]

Server 10.3.1, SDE gdb has archiving and editor tracking enabled.

Secured feature service using built-in token store; server is not federated.

Feat. service added to AGOL, with service credentials stored with item.

Several successful sync's have been preformed, then Collector started reporting "illegal start of token" errors.

Any advice?

[MiaogengZhang]

I think there are three possible reasons I am aware of:

• 1. In iOS, you will meet this error if you have a Server feature service added as an item with stored credentials in ArcGIS Online. The feature service has attachment enabled. Then you add picture attachment made from photo library instead of camera.
• 2. This issue could be related to network. If you are using Web Adapter, try to increased the uploadReadAheadSize value on IIS and sometimes that was enough to fix the issue
• 3. time-out due to huge uploads (greater than a few GB on fast networks and greater than 100 MB on slower networks)

I am thinking if it may be related to reason #1.

[danbecker]

I checked with field staff and new photos were always captured, never added from library, so we can rule out #1.

Since several prior sync's worked, I'm guessing it's either #2 or #3.

What is a good value for uploadReadAheadSize ? It's currently the default value 49152 byes. MS docs say 0 - 2147483647 bytes are acceptable values.

[MiaogengZhang]

Modify the “uploadReadAheadSize” section to be like 20 million (the value there is in Bytes).