Bad JSON: expected object value. exception while uplaoding a file using dropbox Java SDK

Question

Hi all,&nbsp;I am trying to upload a file using dropbox Java SDK (version 3.1.5). I amgetting file from a ajax form and then trying to upload it but getting the below exception when calling uploadAndFinish() method.&nbsp;com.dropbox.core.BadResponseException: Bad JSON: expected object value.
 at [Source: ; line: 1, column: 1]
	at com.dropbox.core.DbxRequestUtil.unexpectedStatus(DbxRequestUtil.java:347)
	at com.dropbox.core.DbxRequestUtil.unexpectedStatus(DbxRequestUtil.java:324)
	at com.dropbox.core.DbxUploader.finish(DbxUploader.java:268)
	at com.dropbox.core.DbxUploader.uploadAndFinish(DbxUploader.java:126)
	at com.dropbox.core.DbxUploader.uploadAndFinish(DbxUploader.java:96)
	at com.dropbox.core.v2.DbxUploadStyleBuilder.uploadAndFinish(DbxUploadStyleBuilder.java:92)
	at com.muletutorials.dropbox.DropboxService.uploadFile(DropboxService.java:81)
	at com.muletutorials.controller.MuletutorialsController.uploadArticle(MuletutorialsController.java:317)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.invokeHandlerMethod(HandlerMethodInvoker.java:175)
	at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:446)
	at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:434)
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:938)
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:870)
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:961)
	at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:863)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:660)
	at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:837)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:316)
	at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:126)
	at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:90)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
	at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:114)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
	at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:122)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
	at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:111)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
	at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:169)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
	at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:48)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
	at org.springframework.security.web.authentication.www.BasicAuthenticationFilter.doFilterInternal(BasicAuthenticationFilter.java:213)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:108)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
	at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:64)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:108)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
	at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:53)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:108)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
	at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:91)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
	at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:213)
	at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:176)
	at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:344)
	at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:261)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:543)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81)
	at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:690)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:615)
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:818)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1627)
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:748)
Caused by: com.fasterxml.jackson.core.JsonParseException: expected object value.
 at [Source: ; line: 1, column: 1]
	at com.dropbox.core.stone.StoneSerializer.expectStartObject(StoneSerializer.java:91)
	at com.dropbox.core.ApiErrorResponse$Serializer.deserialize(ApiErrorResponse.java:53)
	at com.dropbox.core.ApiErrorResponse$Serializer.deserialize(ApiErrorResponse.java:36)
	at com.dropbox.core.stone.StoneSerializer.deserialize(StoneSerializer.java:55)
	at com.dropbox.core.DbxRequestUtil.unexpectedStatus(DbxRequestUtil.java:343)
	... 74 moreThis is what I have tried yetpublic boolean uploadFile(StringBuilder fileName, InputStream fileStream) throws DbxException {
		DbxClientV2 client = createClient();
		String path = "/" + fileName.toString();
		try {
			System.out.println("STARTING...............");
			UploadBuilder ub = client.files().uploadBuilder(path);
			System.out.println("ub done");
			ub.withMode(WriteMode.ADD);
			System.out.println("write mode done");
			FileMetadata metadata = ub.uploadAndFinish(fileStream);
			System.out.println("File Uploaded");
			System.out.println(metadata.toStringMultiline());
			System.out.println("FINISHED...............");
			return true;
		} catch (IOException e) {
			e.printStackTrace();
		}
		return false;
	}The code works till write Mode Done logger. It is failing at the next call, don't know what I am doing wrong.&nbsp;Please help !!!

Greg-DB · Answer

Thanks for following up. That actually sounds like a bug in the SDK then. The SDK should automatically convert the 'invalid_access_token' error response to a proper exception. I'll look into it and ask the team to fix that up.

FilipRachunek · Answer

Hello,&nbsp;I have the same problem, using Dropbox Java SDK 3.1.5. I suspect the issue could be related to new short-lived access tokens and scoped apps, as I don't see this error with "no expiration" token and "full Dropbox" permission type (created in the past).&nbsp;So, my first idea was that some scoped permissions were missing, as all read operations work fine, and the problem occurs only with "uploadAndFinish(inputStream)" method. However, I checked the permissions and I didn't see anything wrong there - there are checked checkboxes at files.metadata.write, files.metadata.read, files.content.write, files.content.read.&nbsp;Can you help, please? I am out of ideas.&nbsp;Filip

Greg-DB · Answer

[Cross-linking for reference:&nbsp;https://stackoverflow.com/questions/63973139/bad-json-expected-object-value-dropbox-api-file-upload-error ]
&nbsp;
Thanks for the report! This error doesn't reproduce for me with this code though, so we'll need to investigate more. Does this error occur for you when uploading to any file path, or just some path(s) in particular?

Abhay Yadav · Answer

I debugged the flow and found the issue. When calling the uploadAndFinish(), somehwere down the line, the API was returning 401 status code, the stack trace was not much helpful though to get the root cause.

I regenerated the access token and it worked!!!

Greg-DB · Answer

FilipRachunek&nbsp;This is a bug in the Java SDK. This is still open with engineering, but I don't have an update on it yet. I'll follow up here once I do.

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Bad JSON: expected object value. exception while uplaoding a file using dropbox Java SDK

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