[Bug]: MSSQL datasource fails with SSL handshake while server does not require encryption

[martin220485]

Is there an existing issue for this?

• I have searched the existing issues

Description

MSSQL datasource fails with SSL handshake while server does not require encryption

Environment

Appsmith version: v1.97
Deployment: Docker self-hosted
Image: appsmith/appsmith-ce:latest
Host OS: Ubuntu 24.04

SQL Server:

Microsoft SQL Server 2016 SP3-GDR
13.0.6475.1
Windows Server 2012 R2

SQL Server network configuration:

TCP Enabled
Port: 1433
Force Encryption: No

---

Problem

When testing an MSSQL datasource, Appsmith fails during connection pool initialization with an SSL handshake error.

Error shown in Appsmith UI:

Failed to initialize pool:
The driver could not establish a secure connection to SQL Server
by using Secure Sockets Layer (SSL) encryption.

---

Container logs

Appsmith container log:

com.microsoft.sqlserver.jdbc.SQLServerException:
The driver could not establish a secure connection to SQL Server
by using Secure Sockets Layer (SSL) encryption.

Caused by: javax.net.ssl.SSLException:
SQL Server did not return a response. The connection has been closed.

at com.microsoft.sqlserver.jdbc.TDSChannel.enableSSL(IOBuffer.java:1906)
at com.microsoft.sqlserver.jdbc.SQLServerConnection.connectHelper(SQLServerConnection.java:3329)
at com.microsoft.sqlserver.jdbc.SQLServerConnection.login(SQLServerConnection.java:2950)

Datasource creation fails at:

HikariPool - Exception during pool initialization
com.external.plugins.MssqlPlugin.createConnectionPool

---

Network connectivity verification

From the Appsmith host:

nc -zv 192.168.1.100 1433
Connection succeeded

---

SQL Server configuration

Verified:

Force Encryption = No
TCP enabled
Port = 1433

---

Connection works from other clients

Connection using DBeaver works with the same parameters:

Host: 192.168.1.100
Port: 1433
Database: database
Authentication: SQL Server authentication
User: user

No SSL settings required.

---

Appsmith datasource configuration

Host: 192.168.1.100
Port: 1433
Database: database
Username: user

SSL mode: Disabled
Prepared statements: Disabled

Despite SSL being disabled in the UI, logs show the JDBC driver calling:

TDSChannel.enableSSL

which suggests TLS negotiation is still attempted.

---

Expected behaviour

When SSL mode is Disabled, the MSSQL plugin should create a non-encrypted connection (equivalent to JDBC encrypt=false).

---

Actual behaviour

The driver attempts TLS handshake anyway and the connection fails.

---

Additional info

The MSSQL plugin used is:

/opt/appsmith/server/mongo/plugins/mssqlPlugin-v1.97.jar

---

Question

Is the MSSQL plugin forcing encrypt=true or attempting TLS negotiation even when SSL mode is set to Disabled?

---

Workaround request

Is there a way to explicitly set JDBC properties such as:

encrypt=false
trustServerCertificate=true

for the MSSQL datasource?

---

Steps To Reproduce

1. Deploy Appsmith v1.97 using Docker.

docker run -d \
--name appsmith \
-p 80:80 \
-p 443:443 \
appsmith/appsmith-ce:latest

2. Login to Appsmith.

3. Create a new datasource.

4. Select Microsoft SQL Server.

5. Configure the datasource with the following parameters:

Host: 192.168.1.100
Port: 1433
Database: database
Username: user
Password: password

SSL Mode: Disabled
Prepared Statements: Disabled

6. Click Test connection.

---

Result

Connection fails and Appsmith logs show:

HikariPool - Exception during pool initialization

com.microsoft.sqlserver.jdbc.SQLServerException:
The driver could not establish a secure connection to SQL Server
by using Secure Sockets Layer (SSL) encryption.

Caused by: javax.net.ssl.SSLException:
SQL Server did not return a response. The connection has been closed.

at com.microsoft.sqlserver.jdbc.TDSChannel.enableSSL

---

Network verification

The SQL Server is reachable from the Appsmith host:

nc -zv 192.168.1.100 1433
Connection succeeded

---

Additional verification

Connection with the same parameters works correctly using DBeaver.

Public Sample App

No response

Environment

Production

Severity

Critical (Broken Production apps)

Issue video log

No response

Version

Self Hosted - 1.97

[linear]

APP-15003