# How to catch a null\_pointer\_exception?
**URL:** https://discuss.elastic.co/t/how-to-catch-a-null-pointer-exception/353921
**Category:** Kibana
**Tags:** painless
**Created:** [February 22, 2024, 8:25pm UTC](https://discuss.elastic.co/t/how-to-catch-a-null-pointer-exception/353921 "2024-02-22T20:25:37Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@catalin8](https://discuss.elastic.co/u/catalin8)
#### Post date: [February 22, 2024, 8:25pm UTC](https://discuss.elastic.co/t/how-to-catch-a-null-pointer-exception/353921/1 "2024-02-22T20:25:37Z")
On a reindex operation I'm using
```auto
if(ctx._source.containsKey("author")) {
ctx._source.title = ctx._source.title + ctx._source.author[0];
ctx._source.remove("author");
}
```
Which throws a null pointer exception error:
```auto
"lang":"painless","caused_by":{"type":"null_pointer_exception","reason":null}},"status":400}
```
How can I check which document causes this error? Because I made sure the `author` field exists, is an array, and the 0 index exists, so I have no idea why I still get the null pointer exception
---
### Author:  [@Marius\_Dragomir](https://discuss.elastic.co/u/Marius_Dragomir)
#### Post date: [February 24, 2024, 1:06am UTC](https://discuss.elastic.co/t/how-to-catch-a-null-pointer-exception/353921/2 "2024-02-24T01:06:02Z")
What versions are you working with? You might have documents without the `_source` field. Easiest way to check and fix if that's the case is to wrap it all in another `IF` clause that checks for the `_source` field before everything.
---
### Author:  [@catalin8](https://discuss.elastic.co/u/catalin8)
#### Post date: [February 25, 2024, 5:44pm UTC](https://discuss.elastic.co/t/how-to-catch-a-null-pointer-exception/353921/3 "2024-02-25T17:44:59Z")
I'm using Elasticsearch 7.6 and `ctx._source` always works. But for some reason not when performing a reindex operation.
What I did as a result was to use a query to check if the field exists in the source index.
---
### Author:  [@system](https://discuss.elastic.co/u/system)
#### Post date: [March 24, 2024, 5:45pm UTC](https://discuss.elastic.co/t/how-to-catch-a-null-pointer-exception/353921/4 "2024-03-24T17:45:47Z")
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