diff --git a/lib/diagnostics.js b/lib/diagnostics.js
index 20ee8270e..7030624db 100644
--- a/lib/diagnostics.js
+++ b/lib/diagnostics.js
@@ -32,15 +32,22 @@ exports.makeDiagnostic = makeDiagnostic;
  */
 function addDiagnostic(config, language, diagnostic) {
     const logger = (0, logging_1.getActionsLogger)();
-    const diagnosticsPath = path_1.default.resolve((0, util_1.getCodeQLDatabasePath)(config, language), "diagnostic", "codeql-action");
-    try {
-        // Create the directory if it doesn't exist yet.
-        (0, fs_1.mkdirSync)(diagnosticsPath, { recursive: true });
-        const jsonPath = path_1.default.resolve(diagnosticsPath, `codeql-action-${diagnostic.timestamp}.json`);
-        (0, fs_1.writeFileSync)(jsonPath, JSON.stringify(diagnostic));
+    const databasePath = (0, util_1.getCodeQLDatabasePath)(config, language);
+    const diagnosticsPath = path_1.default.resolve(databasePath, "diagnostic", "codeql-action");
+    // Check that the database exists before writing to it.
+    if ((0, fs_1.existsSync)(databasePath)) {
+        try {
+            // Create the directory if it doesn't exist yet.
+            (0, fs_1.mkdirSync)(diagnosticsPath, { recursive: true });
+            const jsonPath = path_1.default.resolve(diagnosticsPath, `codeql-action-${diagnostic.timestamp}.json`);
+            (0, fs_1.writeFileSync)(jsonPath, JSON.stringify(diagnostic));
+        }
+        catch (err) {
+            logger.warning(`Unable to write diagnostic message to database: ${err}`);
+        }
     }
-    catch (err) {
-        logger.warning(`Unable to write diagnostic message to database: ${err}`);
+    else {
+        logger.info(`Writing a diagnostic for ${language}, but the database at ${databasePath} does not exist yet.`);
     }
 }
 exports.addDiagnostic = addDiagnostic;
diff --git a/lib/diagnostics.js.map b/lib/diagnostics.js.map
index fd86429e2..4f40b3d32 100644
--- a/lib/diagnostics.js.map
+++ b/lib/diagnostics.js.map
@@ -1 +1 @@
-{"version":3,"file":"diagnostics.js","sourceRoot":"","sources":["../src/diagnostics.ts"],"names":[],"mappings":";;;;;;AAAA,2BAA8C;AAC9C,gDAAwB;AAIxB,uCAA6C;AAC7C,iCAA+C;AAmD/C;;;;;;;GAOG;AACH,SAAgB,cAAc,CAC5B,EAAU,EACV,IAAY,EACZ,OAA+C,SAAS;IAExD,OAAO;QACL,GAAG,IAAI;QACP,SAAS,EAAE,IAAI,EAAE,SAAS,IAAI,IAAI,IAAI,EAAE,CAAC,WAAW,EAAE;QACtD,MAAM,EAAE,EAAE,GAAG,IAAI,EAAE,MAAM,EAAE,EAAE,EAAE,IAAI,EAAE;KACtC,CAAC;AACJ,CAAC;AAVD,wCAUC;AAED;;;;;GAKG;AACH,SAAgB,aAAa,CAC3B,MAAc,EACd,QAAkB,EAClB,UAA6B;IAE7B,MAAM,MAAM,GAAG,IAAA,0BAAgB,GAAE,CAAC;IAClC,MAAM,eAAe,GAAG,cAAI,CAAC,OAAO,CAClC,IAAA,4BAAqB,EAAC,MAAM,EAAE,QAAQ,CAAC,EACvC,YAAY,EACZ,eAAe,CAChB,CAAC;IAEF,IAAI,CAAC;QACH,gDAAgD;QAChD,IAAA,cAAS,EAAC,eAAe,EAAE,EAAE,SAAS,EAAE,IAAI,EAAE,CAAC,CAAC;QAEhD,MAAM,QAAQ,GAAG,cAAI,CAAC,OAAO,CAC3B,eAAe,EACf,iBAAiB,UAAU,CAAC,SAAS,OAAO,CAC7C,CAAC;QAEF,IAAA,kBAAa,EAAC,QAAQ,EAAE,IAAI,CAAC,SAAS,CAAC,UAAU,CAAC,CAAC,CAAC;IACtD,CAAC;IAAC,OAAO,GAAG,EAAE,CAAC;QACb,MAAM,CAAC,OAAO,CAAC,mDAAmD,GAAG,EAAE,CAAC,CAAC;IAC3E,CAAC;AACH,CAAC;AAzBD,sCAyBC"}
\ No newline at end of file
+{"version":3,"file":"diagnostics.js","sourceRoot":"","sources":["../src/diagnostics.ts"],"names":[],"mappings":";;;;;;AAAA,2BAA0D;AAC1D,gDAAwB;AAIxB,uCAA6C;AAC7C,iCAA+C;AAmD/C;;;;;;;GAOG;AACH,SAAgB,cAAc,CAC5B,EAAU,EACV,IAAY,EACZ,OAA+C,SAAS;IAExD,OAAO;QACL,GAAG,IAAI;QACP,SAAS,EAAE,IAAI,EAAE,SAAS,IAAI,IAAI,IAAI,EAAE,CAAC,WAAW,EAAE;QACtD,MAAM,EAAE,EAAE,GAAG,IAAI,EAAE,MAAM,EAAE,EAAE,EAAE,IAAI,EAAE;KACtC,CAAC;AACJ,CAAC;AAVD,wCAUC;AAED;;;;;GAKG;AACH,SAAgB,aAAa,CAC3B,MAAc,EACd,QAAkB,EAClB,UAA6B;IAE7B,MAAM,MAAM,GAAG,IAAA,0BAAgB,GAAE,CAAC;IAClC,MAAM,YAAY,GAAG,IAAA,4BAAqB,EAAC,MAAM,EAAE,QAAQ,CAAC,CAAC;IAC7D,MAAM,eAAe,GAAG,cAAI,CAAC,OAAO,CAClC,YAAY,EACZ,YAAY,EACZ,eAAe,CAChB,CAAC;IAEF,uDAAuD;IACvD,IAAI,IAAA,eAAU,EAAC,YAAY,CAAC,EAAE,CAAC;QAC7B,IAAI,CAAC;YACH,gDAAgD;YAChD,IAAA,cAAS,EAAC,eAAe,EAAE,EAAE,SAAS,EAAE,IAAI,EAAE,CAAC,CAAC;YAEhD,MAAM,QAAQ,GAAG,cAAI,CAAC,OAAO,CAC3B,eAAe,EACf,iBAAiB,UAAU,CAAC,SAAS,OAAO,CAC7C,CAAC;YAEF,IAAA,kBAAa,EAAC,QAAQ,EAAE,IAAI,CAAC,SAAS,CAAC,UAAU,CAAC,CAAC,CAAC;QACtD,CAAC;QAAC,OAAO,GAAG,EAAE,CAAC;YACb,MAAM,CAAC,OAAO,CAAC,mDAAmD,GAAG,EAAE,CAAC,CAAC;QAC3E,CAAC;IACH,CAAC;SAAM,CAAC;QACN,MAAM,CAAC,IAAI,CACT,4BAA4B,QAAQ,yBAAyB,YAAY,sBAAsB,CAChG,CAAC;IACJ,CAAC;AACH,CAAC;AAjCD,sCAiCC"}
\ No newline at end of file
diff --git a/src/diagnostics.ts b/src/diagnostics.ts
index 76cc4c98a..e7ece8f01 100644
--- a/src/diagnostics.ts
+++ b/src/diagnostics.ts
@@ -1,4 +1,4 @@
-import { mkdirSync, writeFileSync } from "fs";
+import { existsSync, mkdirSync, writeFileSync } from "fs";
 import path from "path";
 
 import { Config } from "./config-utils";
@@ -87,23 +87,31 @@ export function addDiagnostic(
   diagnostic: DiagnosticMessage,
 ) {
   const logger = getActionsLogger();
+  const databasePath = getCodeQLDatabasePath(config, language);
   const diagnosticsPath = path.resolve(
-    getCodeQLDatabasePath(config, language),
+    databasePath,
     "diagnostic",
     "codeql-action",
   );
 
-  try {
-    // Create the directory if it doesn't exist yet.
-    mkdirSync(diagnosticsPath, { recursive: true });
+  // Check that the database exists before writing to it.
+  if (existsSync(databasePath)) {
+    try {
+      // Create the directory if it doesn't exist yet.
+      mkdirSync(diagnosticsPath, { recursive: true });
 
-    const jsonPath = path.resolve(
-      diagnosticsPath,
-      `codeql-action-${diagnostic.timestamp}.json`,
-    );
+      const jsonPath = path.resolve(
+        diagnosticsPath,
+        `codeql-action-${diagnostic.timestamp}.json`,
+      );
 
-    writeFileSync(jsonPath, JSON.stringify(diagnostic));
-  } catch (err) {
-    logger.warning(`Unable to write diagnostic message to database: ${err}`);
+      writeFileSync(jsonPath, JSON.stringify(diagnostic));
+    } catch (err) {
+      logger.warning(`Unable to write diagnostic message to database: ${err}`);
+    }
+  } else {
+    logger.info(
+      `Writing a diagnostic for ${language}, but the database at ${databasePath} does not exist yet.`,
+    );
   }
 }