I have been running MAMP Pro 3.05 successfully in Yosemite up to DP4 on a partition that was a clean install of Yosemite.
I now have run the installer for DP5 over m
I tried that solution and others over and over and did not work until I realised I should be restarting completely MAMP, after doing so, this simple change from envvars to _envvars worked like a charm.
You can completely restart MAMP checking if there's any process going on, open the terminal:
ps -cvx | grep "mysql"
That will output a list of the processes that involves mysql at the time, with a PDI associated, so you only have to take that number and:
kill PDI
Where PDI is the number associated to the process, after that, if you write again the command ps -cvx | grep "mysql" the pointer should be empty.
Once done, only execute MAMP.