Error: Repeated service interruptions - failure processing document: Failed to acquire credits in time

Hi All,
 
I am configured Units job (Manifoldcf 2.14 and ES 7.6.2 and postgres 9.6.10) on server to access files from samba SMBv3 server and used jcifs-ng-2.1.2.jar to be loaded in lib of manifoldcf.
 
After ingesting some records into the index , the got this error in logs :-
 :-Unrecognized SmbException thrown getting document version for smb://store1.directory.intra/folders/UnitsTag1/Hydraulic Engineering/13 HYE Data/morelis/VSS/MatlabTools/data/s/srcaaaaa.a
jcifs.smb.SmbException: Failed to acquire credits in time.
 
Can anybody please help me understand what can be the possible cause of this error. Can it be a network connection issue or something else.
 
For info:- no authority connection/ Active Directory is being used till now. Also the Use SID for security (checkbox on manifoldcf UI):- is UNCHECKED.
 
Any help will be appreciated greatly.
 
Thanks
RItika