VCF 4.x Password Management shows error "Password management operation failed in prevalidation stage"

When trying to perform a password management task In VCF environment, on the Password Management Tab it shows an error: "Password management operation failed in prevalidation stage" as shown below:

Operations manager logs are not conclusive enough but in the SDDC Manager database that it is possible to see in a hidden table a few prevalidation old tasks in failed state. 

To validate the Failed Task. It is necessary to connect to SDDC Manager using SSH and then connect to database operations manager:

1. psql -h localhost -U postgres
2. Connect to operations manager database.
\c operationsmanager
3. List out the prevalidation failed tasks for password management. 
select * from passwordmanager.password_operations where transaction_status='PREVALIDATION_FAILED';

There is an auto rotate or password rotate prevalidation task failed listed in the database. 

In order to fix the issue, follow the below steps:

1. Take a snapshot of SDDC Manager.
2. Connect to Database operations manager:
psql -h localhost -U postgres
\c operationsmanager
3. Delete old prevalidation failed task from the database:
delete from passwordmanager.password_operations where transaction_status='PREVALIDATION_FAILED';
4. Go to the SDDC Manager Web interface and click password management tab. If any old failed task which was not cleaned in the past will be visible. 
5. Click Cancel and it should be possible to perform now all password management task.

These solution steps should be applicable on older VCF code too.