diff --git a/core/src/main/java/org/polypheny/db/adapter/DataSource.java b/core/src/main/java/org/polypheny/db/adapter/DataSource.java
index 96aea10ac9..dc226f51f9 100644
--- a/core/src/main/java/org/polypheny/db/adapter/DataSource.java
+++ b/core/src/main/java/org/polypheny/db/adapter/DataSource.java
@@ -116,4 +116,7 @@ private AdapterType getAdapterType() {
         return AdapterType.SOURCE;
     }
 
+
+    public void testConnection(){}
+
 }
diff --git a/plugins/csv-adapter/src/main/java/org/polypheny/db/adapter/csv/CsvSource.java b/plugins/csv-adapter/src/main/java/org/polypheny/db/adapter/csv/CsvSource.java
index fc9f821aae..a936de5de3 100644
--- a/plugins/csv-adapter/src/main/java/org/polypheny/db/adapter/csv/CsvSource.java
+++ b/plugins/csv-adapter/src/main/java/org/polypheny/db/adapter/csv/CsvSource.java
@@ -345,4 +345,35 @@ private void addInformationExportedColumns() {
         }
     }
 
+
+    public void testConnection(){
+        File directory = new File(csvDir.getPath());
+
+        // Check if the directory exists
+        if (!directory.exists() ) {
+            throw new Error("The specified path is not a valid directory.");
+        }
+
+        // List all files in the directory
+        File[] files = directory.listFiles();
+        if(files == null)
+            throw new Error("THERE IS NO CSV FILE TO UPLOAD. ");
+
+        int badFiles = 0;
+        if (files != null) {
+            // Check each file if it has a .csv extension
+            for (File file : files) {
+                System.out.println(file.getName());
+                if (!file.isFile() || !file.getName().toLowerCase().endsWith(".csv"))
+                    badFiles++;
+
+            }
+        }
+
+        if(badFiles==files.length)
+            throw new Error("NO VALID CSV FILE FOUND. ");
+
+
+    }
+
 }
diff --git a/plugins/excel-adapter/src/main/java/org/polypheny/db/adapter/excel/ExcelSource.java b/plugins/excel-adapter/src/main/java/org/polypheny/db/adapter/excel/ExcelSource.java
index 660bc62455..2e63975943 100644
--- a/plugins/excel-adapter/src/main/java/org/polypheny/db/adapter/excel/ExcelSource.java
+++ b/plugins/excel-adapter/src/main/java/org/polypheny/db/adapter/excel/ExcelSource.java
@@ -353,4 +353,30 @@ private void addInformationExportedColumns() {
         }
     }
 
+
+    @Override
+    public void testConnection() {
+
+        File directory = new File(excelDir.getPath());
+        // Check if the directory exists
+        if (!directory.exists() ) {
+            shutdown();
+            throw new Error("The specified path is not a valid directory.");
+        }
+        File[] files = directory.listFiles();
+
+        int goodFile=0;
+        for(File file : files){
+            String fileName = file.getName();
+            if(fileName.endsWith( ".xlsx" ) || fileName.endsWith( ".xlsx.gz" ) || fileName.endsWith( ".xls" ) || fileName.endsWith( ".xls.gz" ))
+                goodFile++;
+        }
+        if(goodFile==0){
+            throw new RuntimeException("No Excel sheet found.");
+        }
+
+
+    }
+
+
 }
diff --git a/plugins/file-adapter/src/main/java/org/polypheny/db/adapter/file/source/Qfs.java b/plugins/file-adapter/src/main/java/org/polypheny/db/adapter/file/source/Qfs.java
index 0f0f449820..df66d9d31c 100644
--- a/plugins/file-adapter/src/main/java/org/polypheny/db/adapter/file/source/Qfs.java
+++ b/plugins/file-adapter/src/main/java/org/polypheny/db/adapter/file/source/Qfs.java
@@ -32,8 +32,11 @@
 import java.util.StringJoiner;
 import lombok.Getter;
 import lombok.extern.slf4j.Slf4j;
+import org.apache.calcite.linq4j.AbstractEnumerable;
+import org.apache.calcite.linq4j.Enumerator;
 import org.polypheny.db.adapter.Adapter.AdapterProperties;
 import org.polypheny.db.adapter.Adapter.AdapterSettingString;
+import org.polypheny.db.adapter.AdapterManager;
 import org.polypheny.db.adapter.DataSource;
 import org.polypheny.db.adapter.DeployMode;
 import org.polypheny.db.catalog.entity.CatalogColumnPlacement;
@@ -302,4 +305,13 @@ protected void registerInformationPage( String uniqueName ) {
         }
     }
 
+
+    @Override
+    public void testConnection(){
+
+        if(currentSchema.getConvention().getFileSchema().getRootDir()==null)
+            throw new RuntimeException("The specified QFS root dir does not exist!");
+
+    }
+
 }
diff --git a/plugins/monetdb-adapter/src/main/java/org/polypheny/db/adapter/monetdb/sources/MonetdbSource.java b/plugins/monetdb-adapter/src/main/java/org/polypheny/db/adapter/monetdb/sources/MonetdbSource.java
index d29bbb3589..93abde72da 100644
--- a/plugins/monetdb-adapter/src/main/java/org/polypheny/db/adapter/monetdb/sources/MonetdbSource.java
+++ b/plugins/monetdb-adapter/src/main/java/org/polypheny/db/adapter/monetdb/sources/MonetdbSource.java
@@ -28,6 +28,7 @@
 import org.polypheny.db.adapter.Adapter.AdapterSettingString;
 import org.polypheny.db.adapter.DeployMode;
 import org.polypheny.db.adapter.jdbc.connection.ConnectionFactory;
+import org.polypheny.db.adapter.jdbc.connection.ConnectionHandler;
 import org.polypheny.db.adapter.jdbc.connection.TransactionalConnectionFactory;
 import org.polypheny.db.adapter.jdbc.sources.AbstractJdbcSource;
 import org.polypheny.db.catalog.Adapter;
@@ -38,6 +39,9 @@
 import org.polypheny.db.schema.Table;
 import org.polypheny.db.sql.language.SqlDialect;
 import org.polypheny.db.sql.language.dialect.MonetdbSqlDialect;
+import org.polypheny.db.transaction.PUID;
+import org.polypheny.db.transaction.PUID.Type;
+import org.polypheny.db.transaction.PolyXid;
 
 
 @Slf4j
@@ -133,4 +137,22 @@ protected boolean requiresSchema() {
         return true;
     }
 
+
+    @Override
+    public void testConnection(){
+
+        PolyXid randomXid = PolyXid.generateLocalTransactionIdentifier( PUID.randomPUID( Type.NODE ), PUID.randomPUID( Type.TRANSACTION ) );
+        ConnectionHandler connectionHandler = connectionFactory.getConnectionHandler(randomXid);
+
+        // Execute an Postgres query
+        String sql = "SELECT 1";
+
+        try {
+            connectionHandler.executeQuery( sql );
+        } catch ( SQLException e ) {
+            throw new RuntimeException( e );
+        }
+    }
 }
+
+
diff --git a/plugins/mysql-adapter/src/main/java/org/polypheny/db/adapter/jdbc/MysqlSourcePlugin.java b/plugins/mysql-adapter/src/main/java/org/polypheny/db/adapter/jdbc/MysqlSourcePlugin.java
index e817d6f23c..17c1622d23 100644
--- a/plugins/mysql-adapter/src/main/java/org/polypheny/db/adapter/jdbc/MysqlSourcePlugin.java
+++ b/plugins/mysql-adapter/src/main/java/org/polypheny/db/adapter/jdbc/MysqlSourcePlugin.java
@@ -29,6 +29,7 @@
 import org.polypheny.db.adapter.Adapter.AdapterSettingList;
 import org.polypheny.db.adapter.Adapter.AdapterSettingString;
 import org.polypheny.db.adapter.DeployMode;
+import org.polypheny.db.adapter.jdbc.connection.ConnectionHandler;
 import org.polypheny.db.adapter.jdbc.sources.AbstractJdbcSource;
 import org.polypheny.db.catalog.Adapter;
 import org.polypheny.db.catalog.entity.CatalogColumnPlacement;
@@ -37,6 +38,9 @@
 import org.polypheny.db.schema.Schema;
 import org.polypheny.db.schema.Table;
 import org.polypheny.db.sql.language.dialect.MysqlSqlDialect;
+import org.polypheny.db.transaction.PUID;
+import org.polypheny.db.transaction.PUID.Type;
+import org.polypheny.db.transaction.PolyXid;
 
 public class MysqlSourcePlugin extends Plugin {
 
@@ -135,6 +139,22 @@ protected boolean requiresSchema() {
             return false;
         }
 
+
+        @Override
+        public void testConnection(){
+
+            PolyXid randomXid = PolyXid.generateLocalTransactionIdentifier( PUID.randomPUID( Type.NODE ), PUID.randomPUID( Type.TRANSACTION ) );
+            ConnectionHandler connectionHandler = connectionFactory.getConnectionHandler(randomXid);
+
+            // Execute an Postgres query
+            String sql = "SELECT 1";
+
+            try {
+                connectionHandler.executeQuery( sql );
+            } catch ( SQLException e ) {
+                throw new RuntimeException( e );
+            }
+        }
     }
 
-}
\ No newline at end of file
+}
diff --git a/plugins/postgres-adapter/src/main/java/org/polypheny/db/adapter/postgres/source/PostgresqlSource.java b/plugins/postgres-adapter/src/main/java/org/polypheny/db/adapter/postgres/source/PostgresqlSource.java
index f18597a0b7..25af357db5 100644
--- a/plugins/postgres-adapter/src/main/java/org/polypheny/db/adapter/postgres/source/PostgresqlSource.java
+++ b/plugins/postgres-adapter/src/main/java/org/polypheny/db/adapter/postgres/source/PostgresqlSource.java
@@ -27,6 +27,7 @@
 import org.polypheny.db.adapter.Adapter.AdapterSettingList;
 import org.polypheny.db.adapter.Adapter.AdapterSettingString;
 import org.polypheny.db.adapter.DeployMode;
+import org.polypheny.db.adapter.jdbc.connection.ConnectionHandler;
 import org.polypheny.db.adapter.jdbc.sources.AbstractJdbcSource;
 import org.polypheny.db.catalog.Adapter;
 import org.polypheny.db.catalog.entity.CatalogColumnPlacement;
@@ -35,6 +36,9 @@
 import org.polypheny.db.schema.Schema;
 import org.polypheny.db.schema.Table;
 import org.polypheny.db.sql.language.dialect.PostgresqlSqlDialect;
+import org.polypheny.db.transaction.PUID;
+import org.polypheny.db.transaction.PUID.Type;
+import org.polypheny.db.transaction.PolyXid;
 
 
 @Slf4j
@@ -124,4 +128,20 @@ protected boolean requiresSchema() {
         return true;
     }
 
+    @Override
+    public void testConnection(){
+
+        PolyXid randomXid = PolyXid.generateLocalTransactionIdentifier( PUID.randomPUID( Type.NODE ), PUID.randomPUID( Type.TRANSACTION ) );
+        ConnectionHandler connectionHandler = connectionFactory.getConnectionHandler(randomXid);
+
+        // Execute an Postgres query
+        String sql = "SELECT 1";
+
+        try {
+            connectionHandler.executeQuery( sql );
+        } catch ( SQLException e ) {
+            throw new RuntimeException( e );
+        }
+    }
+
 }