Issue: CSRF Token Validation Error. When you are working with custom GW Services or even with standard GW Services if you are not getting proper response from GW system and your Fiori apps do not work and you see errors( see attached screen shots here).
1. update your SAPUI5 libraries to latest SAPUI5 1.14.6 or whatever the
latest version it as this is a moving target. there is a fix for this for this
since UI5 >1.14.3 version.
2. Clear your ITS cache using transaction SITSPMON in Gateway system.
3. Restart Chrome/safari and check the same scenario and you should not see
the problem anymore.
4. If problem is not solved then go to SICF.
5. Select your service.
6. go to change mode.
7. Go to GUI Configuration.
8. Enter parameter–> ~CHECK_CSRF_TOKEN, value: 1
9. Chose Save.
10. Repeat the test in Chrome after clearing cache.