The error, "Illegal start of token," intermittently occurs when synchronizing in Collector for ArcGIS (iOS) through the Web Adaptor.
Last Published: October 23, 2015ArcGIS for Server
Bug ID Number
September 19, 2014
June 11, 2020
ArcGIS for Server
Operating System Version
7 64 Bit
The bug has been fixed. See the Version Fixed and Additional Information, if applicable, for more information.
Resolved with the 10.4 release of ArcGIS Server and/or ArcGIS for Desktop.
Increase the uploadReadAheadSize value on Internet Information Services (IIS) to fix the issue: 1. Launch IIS Manager.2. Select the site that is hosting the web application.3. In the Features section, double-click Configuration Editor.4. Under Section, select 'system.webServer', then 'serverRuntime'.5. Modify the 'uploadReadAheadSize' section to 20 MB (Bytes).6. Click Apply. During the renegotiation step, the entity must be preloaded using Secure Socket Layer (SSL). The result is larger than the default value.