diff --git a/package-lock.json b/package-lock.json
index 0dbdcac..f69825f 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,16 +1,16 @@
 {
 	"name": "git-file-sync",
-	"version": "1.0.6",
+	"version": "1.1.2",
 	"lockfileVersion": 3,
 	"requires": true,
 	"packages": {
 		"": {
 			"name": "git-file-sync",
-			"version": "1.0.6",
+			"version": "1.1.2",
 			"license": "MIT",
 			"dependencies": {
 				"ignore": "^7.0.5",
-				"obsidian": "*"
+				"obsidian": "latest"
 			},
 			"devDependencies": {
 				"@eslint/js": "9.30.1",
diff --git a/src/services/git-service-base.ts b/src/services/git-service-base.ts
index 3cd997e..84f4eca 100644
--- a/src/services/git-service-base.ts
+++ b/src/services/git-service-base.ts
@@ -75,12 +75,47 @@ export abstract class BaseGitService {
 
     protected abstract addAuthHeader(headers: Record<string, string>): void;
 
+    /**
+     * Safely parses a response body as JSON.
+     *
+     * Some servers/proxies return a 2xx (or redirect) response whose body is an
+     * HTML page — a login screen, an SSO redirect, or a proxy/error page — rather
+     * than JSON. Accessing `response.json` directly then throws a cryptic
+     * "Unexpected token '<', \"<!DOCTYPE ...\" is not valid JSON" error. This helper
+     * detects that case and throws a clear, actionable message instead.
+     */
+    protected parseJson<T>(response: RequestUrlResponse): T {
+        const contentType = (response.headers?.['content-type'] ?? response.headers?.['Content-Type'] ?? '').toLowerCase();
+        const bodyText = (response.text ?? '').trimStart();
+        const looksLikeHtml = bodyText.startsWith('<') || contentType.includes('html');
+
+        try {
+            const data = response.json as T;
+            if (data === undefined && looksLikeHtml) throw new Error('non-JSON response');
+            return data;
+        } catch (e) {
+            if (looksLikeHtml) {
+                throw new Error(
+                    'Expected a JSON response from the Git server but received an HTML page ' +
+                    '(likely a login, SSO redirect, or proxy/error page). ' +
+                    'Please check the server URL, your access token, and any network proxy or firewall.'
+                );
+            }
+            throw new Error(`Failed to parse the Git server response as JSON: ${e instanceof Error ? e.message : String(e)}`);
+        }
+    }
+
     protected parseErrorResponse(response: RequestUrlResponse): string {
         try {
             const data = response.json as { message?: string; error?: string };
             return data.message || data.error || JSON.stringify(data);
         } catch {
-            return response.text || 'Unknown error';
+            const bodyText = (response.text ?? '').trim();
+            const contentType = (response.headers?.['content-type'] ?? response.headers?.['Content-Type'] ?? '').toLowerCase();
+            if (bodyText.startsWith('<') || contentType.includes('html')) {
+                return 'Received an HTML page instead of a JSON error (likely a login, redirect, or proxy/error page). Check the server URL, access token, and network proxy.';
+            }
+            return bodyText || 'Unknown error';
         }
     }
 
diff --git a/src/services/github-service.ts b/src/services/github-service.ts
index 2d661b7..dbf888f 100644
--- a/src/services/github-service.ts
+++ b/src/services/github-service.ts
@@ -26,7 +26,7 @@ export class GitHubService extends BaseGitService implements GitServiceInterface
         try {
             const url = `${this.getApiUrl(path)}?ref=${branch}`;
             const response = await this.safeRequest(url, 'GET');
-            const data = response.json as GitHubContentResponse;
+            const data = this.parseJson<GitHubContentResponse>(response);
             
             return {
                 content: this.decodeContent(data.content, path),
@@ -47,14 +47,14 @@ export class GitHubService extends BaseGitService implements GitServiceInterface
         };
 
         const response = await this.safeRequest(url, 'PUT', body);
-        const data = response.json as { content: { path: string, sha: string } };
+        const data = this.parseJson<{ content: { path: string, sha: string } }>(response);
         return { path: data.content.path, sha: data.content.sha };
     }
 
     async listFiles(branch: string, useFilter = true): Promise<string[]> {
         const url = `https://api.github.com/repos/${this.owner}/${this.repo}/git/trees/${branch}?recursive=1`;
         const response = await this.safeRequest(url, 'GET');
-        const data = response.json as GitHubTreeResponse;
+        const data = this.parseJson<GitHubTreeResponse>(response);
         
         if (data.truncated) {
             logger.warn('GitHub tree result is truncated. Some files might not be shown.');
diff --git a/src/services/gitlab-service.ts b/src/services/gitlab-service.ts
index 281e0ef..443056a 100644
--- a/src/services/gitlab-service.ts
+++ b/src/services/gitlab-service.ts
@@ -27,7 +27,7 @@ export class GitLabService extends BaseGitService implements GitServiceInterface
         try {
             const url = `${this.getApiUrl(path)}?ref=${branch}`;
             const response = await this.safeRequest(url, 'GET');
-            const data = response.json as GitLabFileResponse;
+            const data = this.parseJson<GitLabFileResponse>(response);
             
             return {
                 content: this.decodeContent(data.content, path),
@@ -50,7 +50,7 @@ export class GitLabService extends BaseGitService implements GitServiceInterface
 
         const method = sha ? 'PUT' : 'POST';
         const response = await this.safeRequest(url, method, body);
-        const data = response.json as GitLabFileResponse;
+        const data = this.parseJson<GitLabFileResponse>(response);
         return { path: data.file_path };
     }
 
@@ -63,7 +63,7 @@ export class GitLabService extends BaseGitService implements GitServiceInterface
         while (true) {
             const url = `${this.baseUrl}/api/v4/projects/${encodedProjectId}/repository/tree?ref=${branch}&recursive=true&per_page=${perPage}&page=${page}`;
             const response = await this.safeRequest(url, 'GET');
-            const data = response.json as GitLabTreeItem[];
+            const data = this.parseJson<GitLabTreeItem[]>(response);
             
             if (!data || data.length === 0) break;
             
diff --git a/tests/services/git-service-base.test.ts b/tests/services/git-service-base.test.ts
index 8cf6a52..ecb5057 100644
--- a/tests/services/git-service-base.test.ts
+++ b/tests/services/git-service-base.test.ts
@@ -41,6 +41,71 @@ describe('BaseGitService', () => {
         });
     });
 
+    describe('parseJson with non-JSON (HTML) responses', () => {
+        // Simulates Obsidian's real RequestUrlResponse.json getter, which throws
+        // SyntaxError when the body is not valid JSON (e.g. an HTML page).
+        function htmlResponse(status = 200): RequestUrlResponse {
+            return {
+                status,
+                headers: { 'content-type': 'text/html; charset=utf-8' },
+                text: '<!DOCTYPE html><html><body>Login</body></html>',
+                get json(): unknown {
+                    throw new SyntaxError('Unexpected token \'<\', "<!DOCTYPE "... is not valid JSON');
+                },
+            } as unknown as RequestUrlResponse;
+        }
+
+        it('getFile: throws a clear error when the server returns an HTML page (2xx)', async () => {
+            vi.mocked(requestUrl).mockResolvedValue(htmlResponse(200));
+            await expect(service.getFile('test.md', 'main')).rejects.toThrow(/received an HTML page/);
+            // The cryptic JSON parse error must not leak through.
+            await expect(service.getFile('test.md', 'main')).rejects.not.toThrow(/Unexpected token/);
+        });
+
+        it('listFiles: throws a clear error when the server returns an HTML page (2xx)', async () => {
+            vi.mocked(requestUrl).mockResolvedValue(htmlResponse(200));
+            await expect(service.listFiles('main')).rejects.toThrow(/received an HTML page/);
+        });
+
+        it('detects HTML by leading "<" even without an html content-type', async () => {
+            vi.mocked(requestUrl).mockResolvedValue({
+                status: 200,
+                headers: {},
+                text: '  <!DOCTYPE html>...',
+                get json(): unknown {
+                    throw new SyntaxError("Unexpected token '<'");
+                },
+            } as unknown as RequestUrlResponse);
+            await expect(service.listFiles('main')).rejects.toThrow(/received an HTML page/);
+        });
+
+        it('reports a generic JSON parse failure for malformed (non-HTML) JSON', async () => {
+            vi.mocked(requestUrl).mockResolvedValue({
+                status: 200,
+                headers: { 'content-type': 'application/json' },
+                text: '{ "tree": [',
+                get json(): unknown {
+                    throw new SyntaxError('Unexpected end of JSON input');
+                },
+            } as unknown as RequestUrlResponse);
+            await expect(service.listFiles('main')).rejects.toThrow(/Failed to parse the Git server response as JSON/);
+        });
+
+        it('parseErrorResponse: surfaces a clear message for an HTML error page (>=400)', async () => {
+            vi.mocked(requestUrl).mockResolvedValue({
+                status: 502,
+                headers: { 'content-type': 'text/html' },
+                text: '<!DOCTYPE html><html><body>Bad Gateway</body></html>',
+                get json(): unknown {
+                    throw new SyntaxError("Unexpected token '<'");
+                },
+            } as unknown as RequestUrlResponse);
+            await expect(service.listFiles('main')).rejects.toThrow(/Received an HTML page instead of a JSON error/);
+            // The raw HTML document must not be dumped into the message.
+            await expect(service.listFiles('main')).rejects.not.toThrow(/DOCTYPE/);
+        });
+    });
+
     describe('encodeContent / decodeContent round-trip', () => {
         it('should correctly encode and decode UTF-8 content', async () => {
             const original = 'Hello, 世界! 🌍';