i've production network with Catalyst 3750G in core and dozens access layer switches Catalyst 3560. I'm going to convert pvst mode into rapid-pvst mode. Does it can broke my network or not?
From Cisco doc on migrating to rapid-pvst from pvst.
Rapid-PVST+ uses the same BPDU format as the 802.1D and it is backward compatible. It is difficult to convert all the switches in the enterprise network at the same time to rapid-PVST+. Because of the backward compatibility, you can convert phase by phase.
---> It is recommended to implement the changes in the scheduled maintenance window because the spanning tree reconfiguration disrupts the traffic flow. <---
Spanning Tree UplinkFast and BackboneFast features are PVST+ features. These are disabled when you enable rapid-PVST+ because those features are built within rapid-PVST+. Therefore, during the migration you can remove those commands. The configuration of the features such as PortFast, BPDUguard, BPDUfilter, root guard, and loopguard are applicable in rapid-PVST+ mode also
I would always do this sort of work during a maintenance window if at all possible just to be on the safe side.