Hi,

Could you please verify whether you have any Search domains enabled? 
You can check this by navigating to Solution Manager -> User interface -> Application Search -> Search Domains

You can enable the search domains and then run the sync job for it to work without errors. 
As for the number of unsynchronized domains, the upper limit can be altered from the application monitoring categories.
If the amount of data in your IFS application environment is relatively high, and if the data is being frequently queried, it is better to have application search domains enabled for most frequently queried categories.
 

Best Regards,

Thilini

Refer KBA : 

Thank you Yasas.  I have tried the same.