diff --git a/library/package-manager.js b/library/package-manager.js
index 00693d1..5ac4fc7 100644
--- a/library/package-manager.js
+++ b/library/package-manager.js
@@ -594,41 +594,46 @@ class PackageManager {
      */
     async fetchUrl(url) {
         console.log("Fetch Package from URL: " + url);
-        const client = new CIBuildClient();
-        const packageData = await client.fetchFromUrlSpecific(url);
-
-        // Extract to a temp location to read package.json for name and version
-        const tempKey = `_url_temp_${Date.now()}`;
-        const tempPath = await this.extractToCache(tempKey, 'url', packageData);
-        const tempFullPath = path.join(this.cacheFolder, tempPath);
-
-        // Read package name and version from the extracted package
-        const pkgJsonPath = path.join(tempFullPath, 'package', 'package.json');
-        const pkgJson = JSON.parse(await fs.readFile(pkgJsonPath, 'utf8'));
-        const packageId = pkgJson.name;
-        const version = pkgJson.version;
-
-        if (!packageId || !version) {
-            throw new Error(`Package at ${url} has no name or version in package.json`);
-        }
+        try {
+            const client = new CIBuildClient();
+            const packageData = await client.fetchFromUrlSpecific(url);
+
+            // Extract to a temp location to read package.json for name and version
+            const tempKey = `_url_temp_${Date.now()}`;
+            const tempPath = await this.extractToCache(tempKey, 'url', packageData);
+            const tempFullPath = path.join(this.cacheFolder, tempPath);
+
+            // Read package name and version from the extracted package
+            const pkgJsonPath = path.join(tempFullPath, 'package', 'package.json');
+            const pkgJson = JSON.parse(await fs.readFile(pkgJsonPath, 'utf8'));
+            const packageId = pkgJson.name;
+            const version = pkgJson.version;
+
+            if (!packageId || !version) {
+                throw new Error(`Package at ${url} has no name or version in package.json`);
+            }
 
-        // Use the same cache key format as npm packages
-        const finalName = `${packageId}#${version}`;
-        const finalPath = path.join(this.cacheFolder, finalName);
+            // Use the same cache key format as npm packages
+            const finalName = `${packageId}#${version}`;
+            const finalPath = path.join(this.cacheFolder, finalName);
 
-        // If it already exists, the same package is already loaded - that's a config error
-        try {
-            await fs.access(finalPath);
-            await fs.rm(tempFullPath, { recursive: true, force: true });
-            throw new Error(`Package ${finalName} already exists in cache. Check library config for duplicates (url: ${url})`);
-        } catch (e) {
-            if (e.message.includes('already exists')) throw e;
-            // Doesn't exist yet, rename temp to final
-            await fs.rename(tempFullPath, finalPath);
-        }
+            // If it already exists, the same package is already loaded - that's a config error
+            try {
+                await fs.access(finalPath);
+                await fs.rm(tempFullPath, { recursive: true, force: true });
+                throw new Error(`Package ${finalName} already exists in cache. Check library config for duplicates (url: ${url})`);
+            } catch (e) {
+                if (e.message.includes('already exists')) throw e;
+                // Doesn't exist yet, rename temp to final
+                await fs.rename(tempFullPath, finalPath);
+            }
 
-        this.totalDownloaded = this.totalDownloaded + packageData.length;
-        return finalName;
+            this.totalDownloaded = this.totalDownloaded + packageData.length;
+            return finalName;
+        } catch (error) {
+            console.error(`Error fetching package from URL ${url}: ${error.message}`);
+            throw error;
+        }
     }
 
     /**
diff --git a/tests/tx/library-error-handling.test.js b/tests/tx/library-error-handling.test.js
new file mode 100644
index 0000000..af8f17b
--- /dev/null
+++ b/tests/tx/library-error-handling.test.js
@@ -0,0 +1,98 @@
+const { Library } = require('../../tx/library');
+const path = require('path');
+const fs = require('fs').promises;
+const os = require('os');
+
+describe('Library error handling', () => {
+  let tmpDir;
+  let yamlPath;
+
+  beforeEach(async () => {
+    tmpDir = await fs.mkdtemp(path.join(os.tmpdir(), 'lib-test-'));
+    yamlPath = path.join(tmpDir, 'library.yml');
+  });
+
+  afterEach(async () => {
+    await fs.rm(tmpDir, { recursive: true, force: true });
+  });
+
+  function createLibrary(configFile) {
+    const log = {
+      info: jest.fn(),
+      error: jest.fn(),
+      warn: jest.fn(),
+      debug: jest.fn(),
+    };
+    const stats = { addStat: jest.fn() };
+    return { library: new Library(configFile, undefined, log, stats), log };
+  }
+
+  test('failed source reports which source failed and throws', async () => {
+    await fs.writeFile(yamlPath, [
+      'base:',
+      '  url: https://storage.googleapis.com/tx-fhir-org',
+      'sources:',
+      '  - internal:lang',
+      '  - internal:INVALID_SOURCE',
+      '  - internal:country',
+    ].join('\n'));
+
+    const { library } = createLibrary(yamlPath);
+    const consoleSpy = jest.spyOn(console, 'error').mockImplementation();
+
+    await expect(library.load()).rejects.toThrow();
+
+    // The error message should identify the failing source
+    const errorMessages = consoleSpy.mock.calls.map(c => c[0]);
+    expect(errorMessages.some(msg => msg.includes('INVALID_SOURCE'))).toBe(true);
+
+    consoleSpy.mockRestore();
+  }, 30000);
+
+  test('error message includes source name on fetch failure', async () => {
+    await fs.writeFile(yamlPath, [
+      'base:',
+      '  url: https://storage.googleapis.com/tx-fhir-org',
+      'sources:',
+      '  - npm:nonexistent.package.that.does.not.exist#99.99.99',
+    ].join('\n'));
+
+    const { library } = createLibrary(yamlPath);
+    const consoleSpy = jest.spyOn(console, 'error').mockImplementation();
+
+    await expect(library.load()).rejects.toThrow();
+
+    const errorMessages = consoleSpy.mock.calls.map(c => c[0]);
+    expect(errorMessages.some(msg => msg.includes('nonexistent.package'))).toBe(true);
+
+    consoleSpy.mockRestore();
+  }, 60000);
+
+  test('load succeeds with empty sources', async () => {
+    await fs.writeFile(yamlPath, [
+      'base:',
+      '  url: https://storage.googleapis.com/tx-fhir-org',
+      'sources: []',
+    ].join('\n'));
+
+    const { library, log } = createLibrary(yamlPath);
+    await library.load();
+
+    expect(log.error).not.toHaveBeenCalled();
+  }, 30000);
+
+  test('load succeeds with valid sources', async () => {
+    await fs.writeFile(yamlPath, [
+      'base:',
+      '  url: https://storage.googleapis.com/tx-fhir-org',
+      'sources:',
+      '  - internal:lang',
+      '  - internal:country',
+    ].join('\n'));
+
+    const { library } = createLibrary(yamlPath);
+    await library.load();
+
+    expect(library.codeSystemFactories.size).toBeGreaterThanOrEqual(2);
+  }, 30000);
+});
diff --git a/tx/library.js b/tx/library.js
index c1cada9..ddfe622 100644
--- a/tx/library.js
+++ b/tx/library.js
@@ -158,7 +158,12 @@ class Library {
     this.log.info('Fetching Data from '+this.baseUrl);
 
     for (const source of config.sources) {
-      await this.processSource(source, this.packageManager, "fetch");
+      try {
+        await this.processSource(source, this.packageManager, "fetch");
+      } catch (error) {
+        console.error(`Failed to fetch source '${source}': ${error.message}`);
+        throw error;
+      }
     }
 
     this.log.info("Downloaded "+((this.totalDownloaded + this.packageManager.totalDownloaded)/ 1024)+" kB");
@@ -167,13 +172,23 @@ class Library {
     this.#logSystemHeader();
 
     for (const source of config.sources) {
-      await this.processSource(source, this.packageManager, "cs");
+      try {
+        await this.processSource(source, this.packageManager, "cs");
+      } catch (error) {
+        console.error(`Failed to load code systems from '${source}': ${error.message}`);
+        throw error;
+      }
     }
     this.log.info('Loading Packages');
     this.#logPackagesHeader();
 
     for (const source of config.sources) {
-      await this.processSource(source, this.packageManager, "npm");
+      try {
+        await this.processSource(source, this.packageManager, "npm");
+      } catch (error) {
+        console.error(`Failed to load package '${source}': ${error.message}`);
+        throw error;
+      }
     }
 
     const endMemory = process.memoryUsage();
diff --git a/tx/library/codesystem.js b/tx/library/codesystem.js
index da3f1ad..872359f 100644
--- a/tx/library/codesystem.js
+++ b/tx/library/codesystem.js
@@ -33,7 +33,12 @@ class CodeSystem extends CanonicalResource {
     // Convert to R5 format internally (modifies input for performance)
     this.jsonObj = codeSystemToR5(this.jsonObj, fhirVersion);
     if (!noMaps) {
-      this.validate();
+      try {
+        this.validate();
+      } catch (e) {
+        const id = this.jsonObj?.url ? `${this.jsonObj.url}|${this.jsonObj.version || ''}` : this.jsonObj?.name || 'unknown';
+        throw new Error(`${e.message} (in ${id})`);
+      }
       this.buildMaps();
     }
   }