as mentioned by the philipp oeser this was not a bug but message can be improved.

the bug was caused due to: If there is no animation at all, the operators poll will fail because of that, returning that generic message.
If there is animation data (but no Euler Rotation F-Curves), the operator will execute, but return early with a bit more descriptive message.

it was solved using : The message could be improved by calling CTX_wm_operator_poll_msg_set with a descriptive text in graphop_editable_keyframes_poll in case ANIM_animdata_filter returns zero items.