appsmithorg/appsmith · critical · AppsmithPluginException

PE-PLG-5002

PE-PLG-5002

Error message

Failed to connect to the in memory database. Unable to perform filtering : {}

What it means

Thrown by the FilterDataServiceCE constructor when DriverManager.getConnection('jdbc:h2:mem:filterDb;DATABASE_TO_UPPER=FALSE') raises SQLException. FilterDataServiceCE is the in-memory H2 engine used to filter/sort query results client-side; if the H2 driver cannot establish the in-memory connection at construction time, every subsequent filter operation is impossible, so the constructor aborts with PLUGIN_IN_MEMORY_FILTERING_ERROR.

Source

Thrown at app/server/appsmith-interfaces/src/main/java/com/appsmith/external/services/ce/FilterDataServiceCE.java:114

                            DataType.LONG,
                            DataType.FLOAT,
                            DataType.DOUBLE,
                            DataType.BOOLEAN,
                            DataType.DATE,
                            DataType.TIME,
                            DataType.TIMESTAMP),
            DataType.DATE, Set.of(),
            DataType.TIMESTAMP, Set.of());

    public FilterDataServiceCE() {

        objectMapper = SerializationUtils.getObjectMapperWithSourceInLocationEnabled();

        try {
            connection = DriverManager.getConnection(URL);
        } catch (SQLException e) {
            log.error(e.getMessage());
            throw new AppsmithPluginException(
                    AppsmithPluginError.PLUGIN_IN_MEMORY_FILTERING_ERROR,
                    "Failed to connect to the in memory database. Unable to perform filtering : " + e.getMessage());
        }
    }

    /**
     * This filter method is using the new UQI format.
     *
     * @param items               - data
     * @param uqiDataFilterParams - filter conditions to apply on data
     * @return filtered data
     */
    public ArrayNode filterDataNew(ArrayNode items, UQIDataFilterParams uqiDataFilterParams) {
        return this.filterDataNew(items, uqiDataFilterParams, null);
    }

    public ArrayNode filterDataNew(
            ArrayNode items, UQIDataFilterParams uqiDataFilterParams, Map<DataType, DataType> dataTypeConversionMap) {

View on GitHub (pinned to 8cd9021c24)

Solutions

Confirm the H2 dependency is on the classpath (com.h2database:h2) and matches the version Appsmith expects.
Check server memory - restart the JVM with a larger heap if OOM preceded the failure.
Inspect the chained SQLException message (it is appended to the error) for the precise H2 failure code.
If running a custom build, ensure no dependency shading strips the H2 driver META-INF/services entry.

Example fix

// before
try {
    connection = DriverManager.getConnection(URL);
} catch (SQLException e) {
    log.error(e.getMessage());
    throw new AppsmithPluginException(
        AppsmithPluginError.PLUGIN_IN_MEMORY_FILTERING_ERROR,
        "Failed to connect to the in memory database. Unable to perform filtering : " + e.getMessage());
}

// after - log full stack and chain the cause
} catch (SQLException e) {
    log.error("H2 in-memory connection failed for URL {}", URL, e);
    throw new AppsmithPluginException(
        AppsmithPluginError.PLUGIN_IN_MEMORY_FILTERING_ERROR,
        "Failed to connect to the in memory database: " + e.getMessage(), e);
}

Defensive patterns

Strategy: try-catch

Validate before calling

// Validate the H2 driver is loadable before constructing FilterDataServiceCE
try {
    Class.forName("org.h2.Driver");
} catch (ClassNotFoundException e) {
    throw new IllegalStateException("H2 JDBC driver missing from classpath; filtering will be unavailable", e);
}
// also verify memory headroom
if (Runtime.getRuntime().freeMemory() < 16L * 1024 * 1024) {
    throw new IllegalStateException("Insufficient heap for in-memory H2 filter DB");
}

Type guard

public static boolean h2DriverAvailable() {
    try {
        Class.forName("org.h2.Driver");
        return true;
    } catch (ClassNotFoundException e) {
        return false;
    }
}

Try / catch

FilterDataServiceCE service;
try {
    service = new FilterDataServiceCE();
} catch (AppsmithPluginException e) {
    log.error("In-memory filter DB unavailable, filtering disabled", e);
    // degrade gracefully: return unfiltered results
    service = null;
}

Prevention

Pin the H2 dependency version Appsmith expects.
Monitor JVM heap; restart under OOM conditions.
Ensure dependency shading does not strip H2's META-INF/services entry.

When it happens

Trigger: H2 JDBC driver missing from the classpath, the JVM out of memory (the in-memory DB cannot allocate), an H2 version conflict where the URL format is rejected, file-system / tmp issues for H2 shadow files, or another classloader already holding an incompatible H2 instance.

Common situations: Running Appsmith in a container where the H2 dependency was shaded out; OOM conditions under heavy load; a custom Appsmith build that excludes the h2 dependency; JDK upgrade that breaks the bundled H2 driver.

Related errors

AI-assisted analysis of appsmithorg/appsmith@8cd9021c24 (2026-08-12). Data as JSON: /api/errors/03533e2ff0e44594. Report an issue: GitHub.