ORA-00059: maximum number of DB_FILES exceeded

When trying to copy PDB using
SQL> create pluggable database TARGET_PDB from SOURCE_PDB;
you may face this error

the solution is very simple,
you need to increase the parmarter  DB_FILES


SQL> show parameter db_files;

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
db_files                             integer     200

key points:

when PDB is closed - the files still exists but you won't see them when counting from 

CDB_DATA_FILES view.

to  drop a pluggabe database including his datafiles use this command:

SQL> drop pluggable database PDB_NAME including datafiles;