I am seeing this error, but only when validating a change set uploaded to production. In the sandbox, the test code runs without issue. One difference is that the production system has around 8k of entries to process, while the sandbox has barely a hundred. I tried adding a batch size setting of 10k to cover that, but it didn't seem to make a difference. Also this is based on similar code that had no problem in production previously so it does lead me to wonder if one of the recent releases may be affecting this.

Here is the essential class that is being tested. Application__c is a custom object that has a Master-detail relationship with Account (or schools). The goal is to grant users/employees of the school Accounts permissions to Contacts that have Applications connected to those school Accounts. So College counselors can see the student data for applicants.

global class AppPermissionBatchService implements Schedulable, Database.Batchable<sObject>, Database.Stateful {
    // This class runs the process of creating Application-based permissions, to give College Partners the permission
    //  to see students for their colleges based on applications rather than student terms. This allows partners to
    //   see students with applications for future attendanced.
	global Map<String, Group> groupMap;
	global Map<String, Map<Id,CommunitiesUserPermissionService.ContactShareMatch>> existingGroupSharingRulesMap;
	global List<ContactShare> csList;

	global static String scheduleBatchJob(String cron) {
    AppPermissionBatchService SC = new AppPermissionBatchService();
    String cron_exp = cron != null ? cron : '0 0 0/1 1/1 * ? *';
    return System.schedule('Application based Permissions Batch Job', cron_exp, SC);
  }

  global static void executeBatchOnDemand(Integer batchSize) {
    AppPermissionBatchService batch = new AppPermissionBatchService();
  	Id batchprocessId = Database.executeBatch(batch, batchSize);
  }

	global void execute(SchedulableContext sc) {
    Id batchprocessId = Database.executeBatch(this, 1000);
  }

	global AppPermissionBatchService() {

	}

	global Database.QueryLocator start(Database.BatchableContext BC) {
		CommunitiesUserPermissionService.userPermissionsForCommunity();
		groupMap = CommunitiesUserPermissionService.getUniversityGroups();
		existingGroupSharingRulesMap = CommunitiesUserPermissionService.getExistingGroupSharingRules(groupMap);
		csList = new List<ContactShare>();
		return Database.getQueryLocator([Select Id, student_name__c, School_Name__c, Mid_Year_Transfer_School__c,
                                         Application_Submission_Year__c,
                                         School_Name__r.recordtype.name,
                                         Mid_Year_Transfer_School__r.recordtype.name
                                       	From Application__c
                                        Where LastModifiedDate = LAST_N_DAYS:3 AND
                                         ((School_Name__c != null AND 
                                               School_Name__r.recordtype.name LIKE 'College/University') OR
                                         	(Mid_Year_Transfer_School__c != null AND 
                                               Mid_Year_Transfer_School__r.recordtype.name LIKE 'College/University'))
                                        ]);
	}

    global void checkCollege(ID college,ID studentID){
        CommunitiesUserPermissionService.ContactShareMatch existingContactSharingRule = null;
        if(existingGroupSharingRulesMap.get(groupMap.get('grp_' + college).Id) != null) {
            existingContactSharingRule = existingGroupSharingRulesMap.get(groupMap.get('grp_' + college).Id).get(studentID);
        }
        
        if (existingContactSharingRule == null) {
            system.debug('making sharing rule');
            ContactShare cs = new ContactShare();
            cs.contactAccessLevel = 'Edit';
            cs.userOrGroupId = groupMap.get('grp_' + college).Id;
            cs.contactId = studentID;
            csList.add(cs);
            CommunitiesUserPermissionService.ContactShareMatch csm = new CommunitiesUserPermissionService.ContactShareMatch();
            csm.matchFound = true;
            csm.rule = cs;
            if(existingGroupSharingRulesMap.get(groupMap.get('grp_' + college).Id) == null) {
                existingGroupSharingRulesMap.put(groupMap.get('grp_' + college).Id, new Map<Id,CommunitiesUserPermissionService.ContactShareMatch>());
            }
            existingGroupSharingRulesMap.get(groupMap.get('grp_' + college).Id).put(studentID, csm);
        } else {
            existingContactSharingRule.matchFound = true;
            System.debug('Existing Rule ' + existingContactSharingRule);
        }
    }
         
	global void execute(Database.BatchableContext BC, List<Application__c> scope) {
		for (Application__c ap : scope) {
            // check school_name and Mid_Year_transfer, each calling the same method.
            // 
            System.debug('School Name: '+ap.School_Name__c+', groupMap get result: '+groupMap.get('grp_' + ap.School_Name__c));
			if (ap.School_Name__c != null && groupMap.get('grp_' + ap.School_Name__c) != null) {
				checkCollege(ap.School_Name__c,ap.student_name__c);
			}
            System.debug('School Name: '+ap.Mid_Year_Transfer_School__c+', groupMap get result: '+
                         groupMap.get('grp_' + ap.Mid_Year_Transfer_School__c));
			if (ap.Mid_Year_Transfer_School__c != null && groupMap.get('grp_' + ap.Mid_Year_Transfer_School__c) != null) {
				checkCollege(ap.Mid_Year_Transfer_School__c,ap.student_name__c);
			}
		}
	}

	global void finish(Database.BatchableContext BC) {
		System.debug(csList);
		if (! csList.isEmpty()) insert csList;
	}

}

Note that it and the earlier version of Student Term based permissions both used a Community service class that creates groups:

public with sharing class CommunitiesUserPermissionService {

  public static Map<String, Group> getUniversityGroups() {
    Map<String, Group> groupMap = new Map<String, Group>();
    for (Group g : [SELECT Id, developerName,name FROM Group WHERE type = 'Regular' AND developerName LIKE 'grp_%']) {
      groupMap.put(g.developerName, g);
    }
    return groupMap;
  }

  public class ContactShareMatch {
    public Id contactShareId {get; set;}
    public ContactShare rule {get; set;}
    public Boolean matchFound {get; set;}
  }

  public static Map<String, Map<Id, ContactShareMatch>> getExistingGroupSharingRules(Map<String, Group> groupMap) {
    Map<String, Map<Id, ContactShareMatch>> existingGroupSharingRulesMap = new Map<String, Map<Id, ContactShareMatch>>();
    for (ContactShare cs : [Select Id, contactId, userOrGroupId From ContactShare Where userOrGroupId In :groupMap.values()]) {
      if (existingGroupSharingRulesMap.get(cs.userOrGroupId) == null) {
        existingGroupSharingRulesMap.put(cs.userOrGroupId, new Map<Id, ContactShareMatch>());
      }
      ContactShareMatch csm = new ContactShareMatch();
      csm.contactShareId = cs.Id;
      csm.matchFound = false;
      csm.rule = cs;
      existingGroupSharingRulesMap.get(cs.userOrGroupId).put(cs.contactId, csm);
    }
    return existingGroupSharingRulesMap;
  }

  private static Map<String, Map<Id, GroupMemberMatch>> getExistingGroupMembers(List<User> userList) {
    Map<String, Map<Id, GroupMemberMatch>> groupMemberMap = new Map<String, Map<Id, GroupMemberMatch>>();
    for (GroupMember gm : [SELECT groupId, group.name, userOrGroupId FROM GroupMember WHERE userOrGroupId IN :userList OR group.developerName = 'All_Colleges_Universities']) {
      if (groupMemberMap.get(gm.groupId) == null) {
        groupMemberMap.put(gm.groupId, new Map<Id, GroupMemberMatch>());
      }
      GroupMemberMatch gmm = new GroupMemberMatch();
      gmm.groupMemberId = gm.Id;
      gmm.matchFound = false;
      groupMemberMap.get(gm.groupId).put(gm.userOrGroupId, gmm);
    }
    return groupMemberMap;
  }

  public class GroupMemberMatch {
    public Id groupMemberId {get; set;}
    public Boolean matchFound {get; set;}
  }

  public static void userPermissionsForCommunity() {
    Id collegeRT = Schema.SObjectType.Account.getRecordTypeInfosByName().get('College/University').getRecordTypeId();
//    list<User> userList = [SELECT Id, contact.accountId, contactId, contact.account.recordtypeId, contact.account.name, profile.Id FROM User WHERE contactId != null And profile.Name != 'DSF - Advisor (external)'];
//    The statement above used the profile 'DSF - Advisor (external)', which no longer indicates a partner user. 
    list<User> userList = [SELECT Id, Name, contact.accountId, contactId, contact.account.recordtypeId, contact.account.name, profile.Id 
                           FROM User WHERE contactId != null And profile.Name LIKE 'College - %'];
    Group allUniGroup = [SELECT ID FROM Group WHERE developerName = 'All_Colleges_Universities'];
    Map<String, Group> groupMap = getUniversityGroups();

    List<Group> toCreate = new List<Group>();
    for (User u : userList) {
      system.debug('User: '+u.Name+', Uni: '+u.Contact.Account.Name);
      system.debug('Account Record Type: ' + u.Contact.Account.recordtypeId);
      system.debug('Account ID: ' + u.contact.accountId);
      system.debug('Group Map lookup: ' + groupMap.get('grp_' + u.contact.accountId));
                   
      if (u.contact.account.recordtypeId == collegeRT && u.contact.accountId != null && groupMap.get('grp_' + u.contact.accountId) == null) {
        Group newGroup = new Group();
        newGroup.type = 'Regular';
        newGroup.name = u.contact.account.name;
        newGroup.doesSendEmailToMembers = false;
        newGroup.doesIncludeBosses = true;
        newGroup.developerName = 'grp_' + u.contact.accountId;
        groupMap.put(newGroup.developerName, newGroup);
        toCreate.add(newGroup);
        system.debug('MAKING GROUP ' + newGroup);
      }
    }
    insert toCreate;

    Map<String, Map<Id, GroupMemberMatch>> memberMap = getExistingGroupMembers(userList);
    List<GroupMember> toDelete = new List<GroupMember>();
    List<GroupMember> newMemberList = new List<GroupMember>();
    for (User u : userList) {
      if (u.contact.account.recordtypeId == collegeRT && u.contact.accountId != null && groupMap.get('grp_' + u.contact.accountId) != null) {

        GroupMemberMatch existingGroupMembershipFound = null;
        if (memberMap.get(groupMap.get('grp_' + u.contact.accountId).Id) != null) {
          existingGroupMembershipFound = memberMap.get(groupMap.get('grp_' + u.contact.accountId).Id).get(u.Id);
        }

        if (existingGroupMembershipFound == null) {
          GroupMember gm = new GroupMember();
          gm.userOrGroupID = u.Id;
          gm.groupId = groupMap.get('grp_' + u.contact.accountId).Id;
          newMemberList.add(gm);
          if (memberMap.get(groupMap.get('grp_' + u.contact.accountId).Id) == null) {
            memberMap.put(groupMap.get('grp_' + u.contact.accountId).Id, new Map<Id, GroupMemberMatch>());
          }
          GroupMemberMatch gmm = new GroupMemberMatch();
          gmm.matchFound = true;
          memberMap.get(groupMap.get('grp_' + u.contact.accountId).Id).put(u.Id, gmm);
        } else {
          memberMap.get(groupMap.get('grp_' + u.contact.accountId).Id).get(u.Id).matchFound = true;
        }

        //Add new group to "all colleges" group for reporting access
        if (allUniGroup != null && (memberMap.get(allUniGroup.Id) == null || memberMap.get(allUniGroup.Id).get(u.Id) == null)) {
          GroupMember gg = new GroupMember();
          gg.userOrGroupId = u.Id;
          gg.groupId = allUniGroup.Id;
          newMemberList.add(gg);
          if (memberMap.get(allUniGroup.Id) == null) {
            memberMap.put(allUniGroup.Id, new Map<Id, GroupMemberMatch>());
          }
          GroupMemberMatch gmm = new GroupMemberMatch();
          gmm.matchFound = true;
          memberMap.get(allUniGroup.Id).put(u.Id, gmm);
        } else {
          memberMap.get(allUniGroup.Id).get(u.Id).matchFound = true;
        }
      }
    }

    for (Map<Id, GroupMemberMatch> groupMembers : memberMap.values()) {
      for (GroupMemberMatch membership : groupMembers.values()) {
        if (!membership.matchFound && membership.groupMemberId != null) {
          GroupMember gm = new GroupMember();
          gm.Id = membership.groupMemberId;
          toDelete.add(gm);
        }
      }
    }
    delete toDelete;
    insert newMemberList;
  }
}

And finally the test class that is throwing this error on validate. Note that it is using the executeBatchOnDemand method. (SeeAllData=true) is used in order to pull valid Group and Account information.
 

@isTest(SeeAllData=true)
private class AppPermissionBatchService_Test {
  private static List<Contact> createTestContacts(List<Account> accList) {
    Id stRT = Schema.SObjectType.Contact.getRecordTypeInfosByName().get('Student').getRecordTypeId();
    List<Contact> objList = new List<Contact>();
    for (Integer i = 0; i < accList.size(); i++) {
      for (Integer x = 0; x < 5; x++) {
        Contact obj = new Contact();
        obj.lastName = 'Contact ' + i + '-' + x;
        obj.firstName = 'Test';
        obj.recordTypeId = stRT;
        obj.DPSID__c = accList[i].Id;
        objList.add(obj);
      }
    }
    insert objList;
    return objList;
  }

   private static List<Account> getUniAccounts(Integer testSize) {
    Id collRT = Schema.SObjectType.Account.getRecordTypeInfosByName().get('College/University').getRecordTypeId();
    List<Account> objList = [select Id from Account where recordTypeId = :collRT LIMIT :testSize];
    return objList;
  }

  
  private static List<Application__c> createTestApplications(List<Contact> conList) {
    Id stRT = Schema.SObjectType.Contact.getRecordTypeInfosByName().get('Student').getRecordTypeId();
    List<Application__c> objList = new List<Application__c>();
     for (Integer i = 0; i < conList.size(); i++) {
      if (conList[i].recordTypeId == stRT) {
        Application__c obj = new Application__c();
        obj.student_name__c = conList[i].Id;
        obj.school_name__c = conList[i].DPSID__c;
        objList.add(obj);
      }
    }
    insert objList;
    return objList;
  }

  private static User createTestUser(String userProfileName, Contact con) {
    Profile p = [SELECT Id, name from Profile WHERE Name = :userProfileName];
    User u = new User(Alias = 'ajtant', Email = 'community-org@testorg.com',
                      EmailEncodingKey = 'UTF-8', LastName = 'Testing', LanguageLocaleKey = 'en_US',
                      LocaleSidKey = 'en_US', ProfileId = p.Id, contactId = con.Id,
                      TimeZoneSidKey = 'America/Los_Angeles', 
                      UserName = 'community-org' + String.valueOf(Math.Round(Math.Random() * 1000)) + '@testorg.com');
    return u;
  }

  private static Contact createTestContact(Id contactRecordType, Account acc, String fName) {
    Contact con = new Contact(lastName = 'Tester', firstName = fname, accountId = acc.Id, recordTypeID = contactRecordType);
    insert con;
    return con;
  }

  static testMethod void testAppPermissionBatchService() {
    
    map<String, Id> recordMap = new map<String, Id>();
    for (RecordType rt : [SELECT Id, Name FROM RecordType WHERE (sobjecttype = 'Contact') OR (sobjecttype = 'Account')]) {
      recordMap.put(rt.name, rt.Id);
    }
	Map<String, Group> groupMap = CommunitiesUserPermissionService.getUniversityGroups();

    Integer testSize = 5; // Note that testSize squared Applications will be created.
    List<Account> accList = getUniAccounts(testSize);
    Contact con1 = createTestContact(recordMap.get('General'), accList[0],'mainUser');
    User user1 = createTestUser('College - Student Finance', con1);
    List<Contact> conList = createTestContacts(accList);
    List<Application__c> appList = createTestApplications(conList);
    // Create one extra Account to test CommunitiesUserPermissionService code to create new sharing rules.
    Id collRT = Schema.SObjectType.Account.getRecordTypeInfosByName().get('College/University').getRecordTypeId();
    Account extraUni = new Account(name='Test College01',recordTypeId = collRT);
    insert(extraUni);
    Contact extraCon = createTestContact(recordMap.get('General'), extraUni,'extraUser');
    User extraUser = createTestUser('College - Student Finance', extraCon);
    

	
    Test.startTest();
    AppPermissionBatchService.executeBatchOnDemand(10000);
//    System.schedule('Application based Permissions Batch Job', '0 0 0/1 1/1 * ? *', new AppPermissionBatchService());
    Test.stopTest();
    List<ContactShare> chkShare = [Select Id, contactId, userOrGroupId From ContactShare where contactId in :conList];
    System.debug('chkShare:' + chkShare);
    System.assertEquals(testSize * testSize, chkShare.size());

   }
}