Server Utilities :: ORA-02270 / No Matching Unique Or Primary Key For Column-list

I was cloning a schema user1 as user2 in the same database.

user1 had quota on 2 tablespaces user1_data and user1_index.

I created user with name as user2.

I created tablespace user2_data only and granted user2 unlimited quota on that tablespace only (did not grant him 'resource' role or unlimited tablespace privilege) Now exported user1 schema as follows

exp system/<passowrd> file=/u05/oradata/dump/user1_schema.dmp log=/u05/oradata/dump/user1_schema_exp.log owner=user1 rows=y constraints=y triggers=y indexes=y statistics=none recordlength=65535 compress=no consistent=n grants=y

then imported in in user2 schema as follows

imp system/<password> file=/u05/oradata/dump/user1_schema.dmp log=/u05/oradata/dump/user2_schema_imp.log fromuser=user1 touser=user2 rows=y constraints=y indexes=y statistics=none recordlength=65535 grants=y

during import i encountered following errors for so many constraints

"ALTER TABLE "table2" ADD CONSTRAINT "constraint_name1" FOREIGN KEY ("CTR_ID") REFERENCES "table1" ("CTR_ID") ENABLE NOVALIDATE"
IMP-00003: ORACLE error 2270 encountered
ORA-02270: no matching unique or primary key for this column-list
IMP-00017: following statement failed with ORACLE error 2270:

I found that the it happened as the primary key of table1 was not created for which error was logged in the log file

. . importing table "table1" 19441 rows imported
IMP-00015: following statement failed because the object already exists:
"ALTER TABLE "table1" ADD CONSTRAINT "T1_PK79" PRIMARY KEY ("CTR_"
"ID") USING INDEX PCTFREE 10 INITRANS 2 MAXTRANS 255 STORAGE(INITIAL 65536 F"
"REELISTS 1 FREELIST GROUPS 1) TABLESPACE "USER1_INDEX" LOGGING ENABLE "
. . importing table "table5" 0 rows imported

However, I checked that the T1_PK79 does not exist in the user2 schema though it exists in user1 schema Neither the index for priamry key (T1_PK79) existed in user2 schema not the table <table1> existed before this import Then what could be the reason that I am getting an error "IMP-00015: following statement failed because the object already exists"?

I assume tablespace for index would not be an issue here as other indexes got created properly in user2_index tablespace during this import.

I tried this twice, once with user2 schema and then with user3 schema as well (with different tablespace), but result is the same.

There were no users connected to the database during export and no background jobs were modiying any data in schema user1 while export.