diff --git a/CHANGELOG.md b/CHANGELOG.md
index df5b85f849385868b6eb8e1d7daa605bc1b4e8d8..b8362aff3682a130e28f40286fcb6ce2f0f703cb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,13 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
### Added
+* Related to #146, a new flag for entities and complete transactions:
+ `force-missing-obligatory=[ignore|warn|error]`. The flag overrides the
+ default behavior of the server (throwing an error when an obligatory property
+ is missing). `ignore` just discards the consistency check, `warn` only issues
+ a warning when obligatory properties are missing and `error` throws an error
+ in that case. The flag can be set for the complete transaction and each
+ single entity, while the entity flag takes precedence.
* New EntityState plug-in. The plug-in disabled by default and can be enabled
by setting the server property `EXT_ENTITY_STATE=ENABLED`. See
[!62](https://gitlab.com/caosdb/caosdb-server/-/merge_requests/62) for more
@@ -31,6 +38,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
### Fixed
+* #146 - Default behavior for missing obligatory properties
* #131 - CQL Parsing error when white space characters before some units.
* #134 - CQL Parsing error when multiple white space characters after `FROM`.
* #130 - Error during `FIND ENTITY` when
diff --git a/src/main/java/org/caosdb/server/database/backend/implementation/MySQL/MySQLRuleLoader.java b/src/main/java/org/caosdb/server/database/backend/implementation/MySQL/MySQLRuleLoader.java
deleted file mode 100644
index 8b34fe2aee9a28a3fdeb56c7c7cbc03e53233982..0000000000000000000000000000000000000000
--- a/src/main/java/org/caosdb/server/database/backend/implementation/MySQL/MySQLRuleLoader.java
+++ /dev/null
@@ -1,81 +0,0 @@
-/// *
-// * ** header v3.0
-// * This file is a part of the CaosDB Project.
-// *
-// * Copyright (C) 2018 Research Group Biomedical Physics,
-// * Max-Planck-Institute for Dynamics and Self-Organization Göttingen
-// *
-// * This program is free software: you can redistribute it and/or modify
-// * it under the terms of the GNU Affero General Public License as
-// * published by the Free Software Foundation, either version 3 of the
-// * License, or (at your option) any later version.
-// *
-// * This program is distributed in the hope that it will be useful,
-// * but WITHOUT ANY WARRANTY; without even the implied warranty of
-// * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-// * GNU Affero General Public License for more details.
-// *
-// * You should have received a copy of the GNU Affero General Public License
-// * along with this program. If not, see <https://www.gnu.org/licenses/>.
-// *
-// * ** end header
-// */
-// package org.caosdb.server.database.backend.implementation.MySQL;
-//
-// import static org.caosdb.server.database.DatabaseUtils.bytes2UTF8;
-//
-// import java.sql.PreparedStatement;
-// import java.sql.ResultSet;
-// import java.sql.SQLException;
-// import java.util.ArrayList;
-// import org.caosdb.server.database.access.Access;
-// import org.caosdb.server.database.backend.interfaces.RuleLoaderImpl;
-// import org.caosdb.server.database.exceptions.TransactionException;
-// import org.caosdb.server.database.proto.Rule;
-// import org.caosdb.server.jobs.core.Mode;
-//
-// public class MySQLRuleLoader extends MySQLTransaction implements RuleLoaderImpl {
-//
-// public MySQLRuleLoader(final Access access) {
-// super(access);
-// }
-//
-// public static final String STMT_GET_RULES =
-// "SELECT rules.transaction, rules.criterion, rules.modus from rules where rules.domain_id=?
-// AND rules.entity_id=? AND rules.transaction=?";
-//
-// @Override
-// public ArrayList<Rule> executeNoCache(
-// final Integer domain, final Integer entity, final String transaction)
-// throws TransactionException {
-// try {
-// final PreparedStatement stmt = prepareStatement(STMT_GET_RULES);
-//
-// stmt.setInt(1, domain);
-// stmt.setInt(2, entity);
-// stmt.setString(3, transaction);
-// stmt.execute();
-//
-// final ResultSet rs = stmt.executeQuery();
-// try {
-// final ArrayList<Rule> ret = new ArrayList<Rule>();
-// while (rs.next()) {
-// final Rule r = new Rule();
-// r.mode = Mode.valueOf(bytes2UTF8(rs.getBytes("modus")));
-// r.job = bytes2UTF8(rs.getBytes("criterion"));
-// r.domain = domain;
-// r.entity = entity;
-// r.transaction = transaction;
-// ret.add(r);
-// }
-// return ret;
-// } finally {
-// rs.close();
-// }
-// } catch (final SQLException e) {
-// throw new TransactionException(e);
-// } catch (final ConnectionException e) {
-// throw new TransactionException(e);
-// }
-// }
-// }
diff --git a/src/main/java/org/caosdb/server/database/backend/interfaces/RuleLoaderImpl.java b/src/main/java/org/caosdb/server/database/backend/interfaces/RuleLoaderImpl.java
deleted file mode 100644
index 66fd1abd9286d34964fc0f00096a17eba8dd56e3..0000000000000000000000000000000000000000
--- a/src/main/java/org/caosdb/server/database/backend/interfaces/RuleLoaderImpl.java
+++ /dev/null
@@ -1,33 +0,0 @@
-/// *
-// * ** header v3.0
-// * This file is a part of the CaosDB Project.
-// *
-// * Copyright (C) 2018 Research Group Biomedical Physics,
-// * Max-Planck-Institute for Dynamics and Self-Organization Göttingen
-// *
-// * This program is free software: you can redistribute it and/or modify
-// * it under the terms of the GNU Affero General Public License as
-// * published by the Free Software Foundation, either version 3 of the
-// * License, or (at your option) any later version.
-// *
-// * This program is distributed in the hope that it will be useful,
-// * but WITHOUT ANY WARRANTY; without even the implied warranty of
-// * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-// * GNU Affero General Public License for more details.
-// *
-// * You should have received a copy of the GNU Affero General Public License
-// * along with this program. If not, see <https://www.gnu.org/licenses/>.
-// *
-// * ** end header
-// */
-// package org.caosdb.server.database.backend.interfaces;
-//
-// import java.util.ArrayList;
-// import org.caosdb.server.database.exceptions.TransactionException;
-// import org.caosdb.server.database.proto.Rule;
-//
-// public interface RuleLoaderImpl extends BackendTransactionImpl {
-//
-// public ArrayList<Rule> executeNoCache(Integer domain, Integer entity, String transaction)
-// throws TransactionException;
-// }
diff --git a/src/main/java/org/caosdb/server/database/backend/transaction/RuleLoader.java b/src/main/java/org/caosdb/server/database/backend/transaction/RuleLoader.java
deleted file mode 100644
index 753265f0fb6007de47c0b03e0b8bb5f6a7f47a5c..0000000000000000000000000000000000000000
--- a/src/main/java/org/caosdb/server/database/backend/transaction/RuleLoader.java
+++ /dev/null
@@ -1,96 +0,0 @@
-/// *
-// * ** header v3.0
-// * This file is a part of the CaosDB Project.
-// *
-// * Copyright (C) 2018 Research Group Biomedical Physics,
-// * Max-Planck-Institute for Dynamics and Self-Organization Göttingen
-// * Copyright (C) 2019 IndiScale GmbH
-// * Copyright (C) 2019 Timm Fitschen (t.fitschen@indiscale.com)
-// *
-// * This program is free software: you can redistribute it and/or modify
-// * it under the terms of the GNU Affero General Public License as
-// * published by the Free Software Foundation, either version 3 of the
-// * License, or (at your option) any later version.
-// *
-// * This program is distributed in the hope that it will be useful,
-// * but WITHOUT ANY WARRANTY; without even the implied warranty of
-// * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-// * GNU Affero General Public License for more details.
-// *
-// * You should have received a copy of the GNU Affero General Public License
-// * along with this program. If not, see <https://www.gnu.org/licenses/>.
-// *
-// * ** end header
-// */
-// package org.caosdb.server.database.backend.transaction;
-//
-// import java.util.ArrayList;
-// import org.apache.commons.jcs.access.behavior.ICacheAccess;
-// import org.caosdb.server.caching.Cache;
-// import org.caosdb.server.database.CacheableBackendTransaction;
-// import org.caosdb.server.database.backend.interfaces.RuleLoaderImpl;
-// import org.caosdb.server.database.exceptions.TransactionException;
-// import org.caosdb.server.database.proto.Rule;
-// import org.caosdb.server.entity.EntityInterface;
-// import org.caosdb.server.entity.container.TransactionContainer;
-// import org.caosdb.server.entity.wrapper.Property;
-// import org.caosdb.server.jobs.Job;
-// import org.caosdb.server.transaction.Transaction;
-//
-/// **
-// * Load transaction rules (e.g. "Referenced entities must always exist") and their configuration
-// * from the back-end.
-// *
-// * @author Timm Fitschen (t.fitschen@indiscale.com)
-// */
-// public class RuleLoader extends CacheableBackendTransaction<String, ArrayList<Rule>> {
-//
-// private static final ICacheAccess<String, ArrayList<Rule>> cache =
-// Cache.getCache("BACKEND_JobRules");
-// private final Transaction<? extends TransactionContainer> transaction;
-// private final EntityInterface e;
-// private final Integer entity;
-// private final Integer domain;
-// private ArrayList<Job> jobs;
-// private String transactionType;
-//
-// public RuleLoader(
-// final Integer domain,
-// final Integer entity,
-// final EntityInterface e,
-// final Transaction<? extends TransactionContainer> transaction) {
-// super(cache);
-// this.domain = domain;
-// this.entity = entity;
-// this.e = e;
-// if (e instanceof Property) {
-// this.transactionType = getTransactionType(((Property) e).getDomainEntity());
-// } else {
-// this.transactionType = getTransactionType(e);
-// }
-// this.transaction = transaction;
-// }
-//
-// @Override
-// protected String getKey() {
-// return "<" + this.domain + "," + this.entity + "," + this.transactionType + ">";
-// }
-//
-// public ArrayList<Job> getJobs() {
-// return this.jobs;
-// }
-//
-// @Override
-// public ArrayList<Rule> executeNoCache() throws TransactionException {
-// final RuleLoaderImpl t = getImplementation(RuleLoaderImpl.class);
-// return t.executeNoCache(this.domain, this.entity, this.transactionType);
-// }
-//
-// @Override
-// protected void process(final ArrayList<Rule> t) throws TransactionException {
-// this.jobs = new ArrayList<Job>();
-// for (final Rule r : t) {
-// this.jobs.add(Job.getJob(r.job, r.mode, this.e, this.transaction));
-// }
-// }
-// }