I have two dataframes `df1` and `df2`. Both of them have the following schema:

```
 |-- ts: long (nullable = true)
 |-- id: integer (nullable = true)
 |-- managers: array (nullable = true)
 |    |-- element: string (containsNull = true)
 |-- projects: array (nullable = true)
 |    |-- element: string (containsNull = true)

```

`df1` is created from an avro file while `df2` from an equivalent parquet file. However, If I execute, `df1.unionAll(df2).show()`, I get the following error:

```
    org.apache.spark.sql.AnalysisException: unresolved operator 'Union;
    at org.apache.spark.sql.catalyst.analysis.CheckAnalysis$class.failAnalysis(CheckAnalysis.scala:37)
    at org.apache.spark.sql.catalyst.analysis.Analyzer.failAnalysis(Analyzer.scala:44)
    at org.apache.spark.sql.catalyst.analysis.CheckAnalysis$$anonfun$checkAnalysis$1.apply(CheckAnalysis.scala:174)
    at org.apache.spark.sql.catalyst.analysis.CheckAnalysis$$anonfun$checkAnalysis$1.apply(CheckAnalysis.scala:49)
    at org.apache.spark.sql.catalyst.trees.TreeNode.foreachUp(TreeNode.scala:103)

```