Every time when rendering video using h.264 codec, I get an error

This error may appear in some users who render video directly from After Effects to MOV format, with the h.264 codec

Perhaps this error is related to updates from Adobe developers that affected the h.264 codec, or because QuickTime is no longer supported.

At the moment, we do not have a quick solution to this problem, which could be useful for our customers.
In any case, as a temporary solution, you can try to do the following:

1. Restart After Effects and go to the “Render Queue” panel

2. In the “Output Module” settings, for item that you are going to render, go to the codec setup

3. In the “Video Codec” parameter, instead of h.264, select any other codec. For example Photo JPEG.

After that, try rendering. Next, the rendered media file, you can convert to the format you need with Adobe Media Encoder.