opengrok Index database(s) not found

I'm using OpenGrok and get an issue when I try to search on a project. I get the error "Index database(s) not found..."

It's a bit weird, because there are other projects on this instance and they work perfectly. It's only with the last project in my list that I have this problem...

Does anyone have any idea?

You will see this error, when there is a problem with indexing of given repository. opengrok creates a "dirty" file in such cases under index folder eg. /home/opengrok/data/index/

Please follow the below steps to solve such errors.

1. Identify the repository on which this error is being appeared eg. test

2. Login to opengrok server

3. cd /home/opengrok/data/index/ eg. /home/opengrok/data/index/test

4. Move the contents to a temp location eg. mkdir /tmp/test; mv /home/opengrok/data/index/test/* /tmp/test
5. Start indexing again.