"This place gives me an uncomfortableness." - Jayne Cobb, Firefly - 'Safe'
In checking the archives of my blog, I noticed this posting from September.
There's another way to fix this and for completeness, thought I should post it
Once you've attempted to start the database, you'll get as far as "mounted' before the error message appears. If you can check your alert logs and take the affected tablespaces out of backup mode:
alter tablespace MYTS end backup;
all you'll need to do is to issue "ALTER DATABASE OPEN;" and the database will open.
Either method will work. I've had the opportunity to use both in the last couple of months.