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A wealth of new theoretical and observational evidence supports now the idea that episodic accretion is a fundamental and common phenomenon across mass and time in star formation. In particular comma the most recent discovery and follow-up of three accretion bursts from high mass young stellar objects (HMYSOs) have been key to link low- and high-mass star-formation mechanisms to the common ground of disk-mediated accretion. Among those comma only one (S255IR NIRS 3) could be detected and studied at NIR wavelengths comma just after the burst maximum. A new accretion burst from Mol77 comma a 10 Msun protostar comma begun in the first week of October 2022. This provides us with the unique chance to study such rare events from an early stage. We request HST-WFC3 observations to map the source and its outflow cavity to confirm the burst in the infrared. We will also derive the pre-burst spectrum of Mol77 comma as the cavity walls still see the pre-outburst phase. Finally comma we will for the first time measure the light echo with the HST for a HMYSO.