  Solar magnetic flux rope (MFR) plays a central role in the physics of coronal
mass ejections (CMEs). It mainly includes a cold filament at typical
chromospheric temperatures (10000 K) and a hot channel at high coronal
temperatures (10 MK). The warm MFR at quiescent coronal temperatures of a
million Kelvin is, however, rarely reported. In this study, using
multiwavelength images from Atmospheric Imaging Assembly (AIA) on board the
Solar Dynamic Observatory (SDO) and Extreme Ultraviolet Imager (EUVI) on board
the Solar Terrestrial Relations Observatory-A (STEREO-A), we present an
eruption of a warm channel, that represents an MFR with quiescent coronal
temperatures (0.6-2.5 MK). On 2022 May 8, we observed the failed eruption of a
hot channel, with the average temperature and emission measure (EM) of 10 MK
and 1.1*1028 cm^-5, using AIA high-temperature images in active region (AR)
13007. This failed eruption was associated with a C8.2 flare, with no CME.
Subsequently, we observed a warm channel that appeared in AIA and EUVI
low-temperature images, rather than AIA high-temperature images. It then
erupted, and transformed toward a semi-circular shape. An associated C2.1
flare, along with the signatures of magnetic reconnection in AIA
high-temperature images, were identified. Additionally, we observed a CME
associated with this event. Compared with the hot channel, the warm channel is
cooler and rarer with the average temperature and EM of 1.7 (1.6) MK and
2.0*1026 (2.3*1026) cm^-5. All the results suggest an unambiguous observation
of the million-Kelvin warm MFR, that erupted as a CME, and fill a gap in the
temperature domain of coronal MFRs.
