Roscosmos: Pre-launch tests at Baikonur

Roscosmos and space industry specialists perform pre-launch tests of the Proton-M vehicle with the Spectr-RG observatory at the Baikonur cosmodrome.  In particular, a cycle of planned tests and additional checks of all the launch vehicle systems, the DM-03 upper stage and the observatory are carried out.

However, during the final phase of the ground tests, an issue on the launch missile was revealed, which required additional time to eliminate.

Source: Roscosmos