# OPC tag writes in designer preview mode causing Java Web Launcher error **URL:** \ **Category:** Ignition\ **Created:** [November 1, 2019, 2:39pm UTC](https://forum.inductiveautomation.com/t/opc-tag-writes-in-designer-preview-mode-causing-java-web-launcher-error/29591 "2019-11-01T14:39:34Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![B.Chiaramonte](https://avatars.discourse-cdn.com/v4/letter/b/c6cbf5/32.png) [@B.Chiaramonte](https://forum.inductiveautomation.com/u/B.Chiaramonte)\ **Post date:** [November 1, 2019, 2:39pm UTC](https://forum.inductiveautomation.com/t/opc-tag-writes-in-designer-preview-mode-causing-java-web-launcher-error/29591/1 "2019-11-01T14:39:34Z")
Local gateway running on a Windows 10 64 bit PC. Designer in preview mode can read OPC tags from connected PLC device. Attempting tag writes causes Java™ Web Launcher (32 bit) Error. Can only view error as listed item in Windows Task Manager; i.e. no diagnostic information. Ignition version 7.9.10. ---
**Author:** ![MMaynard](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/mmaynard/32/3366_2.png) [@MMaynard](https://forum.inductiveautomation.com/u/MMaynard)\ **Post date:** [November 1, 2019, 7:05pm UTC](https://forum.inductiveautomation.com/t/opc-tag-writes-in-designer-preview-mode-causing-java-web-launcher-error/29591/2 "2019-11-01T19:05:50Z")
Is the Designer in Read/Write mode? ![TagEditMode](https://us1.discourse-cdn.com/inductiveautomation/original/2X/d/d7c412166805f2414859facc14985bb42bec22b2.png) ---
**Author:** ![B.Chiaramonte](https://avatars.discourse-cdn.com/v4/letter/b/c6cbf5/32.png) [@B.Chiaramonte](https://forum.inductiveautomation.com/u/B.Chiaramonte)\ **Post date:** [November 1, 2019, 8:01pm UTC](https://forum.inductiveautomation.com/t/opc-tag-writes-in-designer-preview-mode-causing-java-web-launcher-error/29591/3 "2019-11-01T20:01:00Z")
No it wasn’t (“D’oh!”) - that seemed to do the trick. Thx a ton Maynard !!