Custom GPT + Google Sheets integration fix
Custom GPTGoogle Apps ScriptGoogle Sheets
A client built a Custom GPT to help students log their work into a Google Sheet. After a few prompt and parameter changes, the integration stopped working. I was hired to fix the Google Apps Script and the GPT action so the data could be appended to the sheet reliably again.
Problem
The GPT was supposed to send structured data to a Google Sheet. After multiple changes, two things broke:
- Google Apps Script stopped accepting the payload
- The Custom GPT action schema no longer matched what the script expected
As a result, no new rows were being logged.
What I did
- Reviewed and corrected the Google Apps Script
- Fixed parameter mismatches and validation errors
- Updated the Custom GPT action schema to match the script
Once updated, the workflow worked consistently again - every entry was added to the Google Sheet without errors.
Result
- Working data logging from Custom GPT to Google Sheets
- Stable Apps Script with proper error handling
- Reliable action calls for students using the tool
Simple fix, stable system, no rebuild required.