After update to version 1.9 IDE, Bus I2C not working. Using IDE 1.8, I2C works fine.

[TDK]

Do a diff on the code between the two and see what's different.

[RDos]

There is no difference, it's the same code.

File ioc was migrated from 6.4 to 6.5

IDE 1.8

HAL 1.16.2

Toolchain 9-2020-q2

IDE 1.9

HAL 1.16.2

Toolchain 10.3-2021.10

[TDK]

If the code is actually the same, has to be the compiler causing changes. Unlikely to be an issue with the GCC compiler, more likely to be a software bug being exposed by slightly different compilations.
Regardless, going to be hard to diagnose without details.

[Pavel A.]

V. 1.9 uses a newer toolchain by default (compiler GCC 10).

[RDos]

using ide 1.9 and Toolchain 9-2020-q2

works well.