# Cause and Fix for the "Error in IO Configuration!" Message

**URL:** <https://www.wago.community/t/cause-and-fix-for-the-error-in-io-configuration-message/2668>\
**Category:** CODESYS\
**Created:** [April 9, 2026, 8:11pm UTC](https://www.wago.community/t/cause-and-fix-for-the-error-in-io-configuration-message/2668 "2026-04-09T20:11:54Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![WagoAlexR](https://avatars.discourse-cdn.com/v4/letter/w/ec9cab/32.png) [@WagoAlexR](https://www.wago.community/u/WagoAlexR)\
**Post date:** [April 9, 2026, 8:11pm UTC](https://www.wago.community/t/cause-and-fix-for-the-error-in-io-configuration-message/2668/1 "2026-04-09T20:11:54Z")

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Recently, we have been seeing a few reports of users experiencing the message below when attempting to run their Codesys project:

 ![image](https://us1.discourse-cdn.com/flex016/uploads/wago/original/2X/4/4d95938d6f65bea117d461c35ca2c276afafb6a2.png)

We have traced this issue to a bug found on both FW28 and FW30 and seems to only occur when downloading a program twice while the run/stop slide switch is set to STOP. This will be corrected in a future firmware update (FW30 Patch 3); however, a simple workaround exists. Keeping the run/stop slide switch to RUN should bypass this issue in the meantime.

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**Author:** ![MikePsaltis](https://sea2.discourse-cdn.com/flex016/user_avatar/www.wago.community/mikepsaltis/32/47_2.png) [@MikePsaltis](https://www.wago.community/u/MikePsaltis)\
**Post date:** [April 9, 2026, 9:22pm UTC](https://www.wago.community/t/cause-and-fix-for-the-error-in-io-configuration-message/2668/2 "2026-04-09T21:22:08Z")

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Setting the Runtime in the WBM from ‘CODESYS V3’, to ‘none”, then back to ‘CODESYS V3‘ has also resolved this for me on a 751-9402 CC100.