> For clean Markdown content of this page, append .md to this URL. For the complete documentation index, see https://buildwithfern.com/learn/llms.txt. ## 4.0.0-rc5 **`(fix):`** Pydantic models now call update forward refs on non-union circular references. This prevents runtime errors in certain cases where types self reference itself through a union. ## 4.0.0-rc4 **`(fix):`** Pydantic models now call update forward refs on non-union circular references. This prevents runtime errors in certain cases where types self reference itself through a union. ## 4.0.0-rc3 **`(fix):`** Pydantic models now call update forward refs on non-union circular references. This prevents runtime errors in certain cases where types self reference itself through a union.