by Ryan Smith.
We saw tons of these errors on our upgrade from 2.4.4 to 2.5 as well. Some errors said Maximum execution time of 300 seconds exceeded, so I restarted the upgrade and then it said maximum execution time of 120 seconds exceeded.
The strangest part is that I have max_execution_time in php.ini set to a huge value, 18000 seconds, so it shouldn't timeout.
We solved the problem by using the command line upgrade tool.