drop table causes ORA-08103 with another one
AskTom (answered by Connor McDonald) : ORA - 08103:Object No Longer Exists and an even more detailed explanation by Connor McDonald: A cool thing with EXCHANGE PARTITION (recommended by AskTom here).

TRUNCATE TABLE is a DDL statement, not a DML statement like delete. But what happens is a phenomena that is similar to a phenomena that can be caused by delete or update  statements.

If   delete or update statements are involved then we have 

ORA-01555: snapshot too old: rollback segment number string with name "string" too small


There is also an AskTom article for ORA-01555



What happens:

Assume in your transaction you start a SELECT statement on a table. During this  select statement another transaction manipulates the data:


Either it deletes or updates  the table data (DML) and commits
or it truncates a partitions or the table or  exchanges a partition (DDL)


In this case your session that executes the select statement cannot find the data on its original place because the table has already changed. But it  is necessary to retrieve the table data in a consistent way, this means not need the data from the table from the point in time when the query started.
YOur session  it may be able to find the data in a rollback segment (in case of a DML  statement) or in the table whose segment you have exchanged with the partition (in case of exchange partition) or it is a segment that is not assigned to a table anymore but is still available and unaltered on disk (DDL statement).
If Oracle finds all the data it can continue with your select statement. If it does not find the data, either because the rollback segment where  already overwritten (DML  case)  or the segment was already modified or deleted (DDL case) then Oracle will throw an error.
in the DML case Oracle will throw an ORA-01555, in the DDL case it will throw a ORA-08103.

Connor McDonald writes in the first article referenced:


  Partitioned tables are the most common scenario to see this error, but by no means the only way. 
  
  Anything that physically alters an underlying segment that is being queried can create the issue. Examples: 
  
  
  truncate table 
  alter table move 
  alter index rebuild 
  


Both articles are very instructive and I recommend you to read both (the second one is a video)

So how can you handle this problem?


simply repeat the action in case of this error (or rollback the transaction and repeat it)
maybe it helps if you wait some time before you drop the exchanged partition. Maybe this will decrease the frequency of this error.