Styling code editor fails

[t-book]

Expected Behavior

A Layer style can be edited several times in code styling window

Actual Behavior

After trying to edit the style second time in code window a saving fails

Steps to Reproduce the Problem

1. Upload a simple point layer on https://stable.demo.geonode.org/
2. Paste a simple sld in the styling code editor and save
3. Go back to the layer
4. Reopen the styling editor and paste the same or a sligthly changed simple SLD

Saving will fail

The Django error is:

The Test is

https://stable.demo.geonode.org/catalogue/#/dataset/10752
test-files.zip

Specifications

• GeoNode version: 4.2.1
• Installation type (vanilla, geonode-project):
• Installation method (manual, docker): Docker
• Platform: Ubuntu
• Additional details: