My solution for upgrading from Postgresql 11 to Postgresql 12 on Windows 10 is the following.
As a first remark you will need to be able stop and start the Postgresql service. You can do this by the following commands in Powershell.
Start:
pg_ctl start -D “d:\postgresql\11\data”
Stop:
pg_ctl stop -D “d:\postgresql\11\data”
Status:
pg_ctl status -D “d:\postgresql\11\data”
It would be wise to make a backup before doing the upgrade. The Postgresql 11 instance must be running. Then to copy the globals do
pg_dumpall -U postgres -g -f d:\bakup\postgresql\11\globals.sql
and then for each database
pg_dump -U postgres -Fc <database> > d:\backup\postgresql\11\<database>.fc
or
pg_dump -U postgres -Fc -d <database> -f d:\backup\postgresql\11\<database>.fc
If not already done install Postgresql 12 (as Postgresql 11 is also installed this will be on port 5433)
Then to do the upgrade as follows:
1) Stop Postgresql 11 service (see above)
2) Edit the postgresql.conf file in d:\postgresql\12\data and change port = 5433 to port = 5432
3) Edit the windows user environment path (windows start then type env) to point to Postgresql 12 instead of Postresql 11
4) Run upgrade by entering the following command.
pg_upgrade `
-b “c:\program files\postgresql\11\bin” `
-B “c:\program files\postgresql\12\bin” `
-d “d:\postgresql\11\data” `
-D “d:\postgresql\12\data” --username=postgres
(In powershell use backtick (or backquote) ` to continue the command on the next line)
5) and finally start the new Postgresql 12 service
pg_ctl start -D “d:\postgresql\12\data”