# com.complexible.stardog.StardogException: java.lang.String cannot be cast to java.lang.Boolean

**URL:** https://community.stardog.com/t/com-complexible-stardog-stardogexception-java-lang-string-cannot-be-cast-to-java-lang-boolean/2070
**Category:** Bug
**Created:** [November 4, 2019, 2:16pm UTC](https://community.stardog.com/t/com-complexible-stardog-stardogexception-java-lang-string-cannot-be-cast-to-java-lang-boolean/2070 "2019-11-04T14:16:34Z")
**Posts on this page:** 7
**Page:** 1

<div class="post-metadata">

### Author: ![earthquakesan](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.stardog.com/earthquakesan/32/421_2.png) [@earthquakesan](https://community.stardog.com/u/earthquakesan)
#### Post date: [November 4, 2019, 2:16pm UTC](https://community.stardog.com/t/com-complexible-stardog-stardogexception-java-lang-string-cannot-be-cast-to-java-lang-boolean/2070/1 "2019-11-04T14:16:34Z")

</div>

After migrating production database (data can not be shared) from Stardog 6 to Stardog 7 -- using backup/restore functionality -- the database throws an exception to a simple `select * where {?s ?p ?o} limit 5` query executed via Stardog Studio:

```auto
ERROR 2019-11-04 13:59:47,739 [stardog-user-8] com.stardog.http.server.undertow.ErrorHandling:writeError(138): Unexpected error on the server
com.complexible.stardog.StardogException: java.lang.String cannot be cast to java.lang.Boolean
	at com.complexible.stardog.StardogKernel.getConnection(StardogKernel.java:1126) ~[stardog-7.0.2.jar:?]
	at com.complexible.stardog.protocols.http.server.KernelHttpService$ConnectionOptions.connect(KernelHttpService.java:117) ~[stardog-protocols-http-server-7.0.2.jar:?]
	at com.complexible.stardog.protocols.http.server.KernelHttpService.openConnection(KernelHttpService.java:68) ~[stardog-protocols-http-server-7.0.2.jar:?]
	at com.complexible.stardog.protocols.http.server.SPARQLProtocol.executeQuery(SPARQLProtocol.java:111) ~[stardog-protocols-http-server-7.0.2.jar:?]
	at com.complexible.stardog.protocols.http.server.SPARQLProtocol.post(SPARQLProtocol.java:92) ~[stardog-protocols-http-server-7.0.2.jar:?]
	at com.stardog.http.server.undertow.jaxrs.ExtractRoutes.lambda$handleIt$5(ExtractRoutes.java:192) ~[stardog-protocols-http-server-7.0.2.jar:?]
	at org.apache.shiro.subject.support.SubjectRunnable.doRun(SubjectRunnable.java:120) [shiro-core-1.3.0.jar:1.3.0]
	at org.apache.shiro.subject.support.SubjectRunnable.run(SubjectRunnable.java:108) [shiro-core-1.3.0.jar:1.3.0]
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:1.8.0_222]
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:1.8.0_222]
	at java.lang.Thread.run(Thread.java:748) [?:1.8.0_222]
Caused by: java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Boolean
	at com.complexible.stardog.StardogKernel.getConnection(StardogKernel.java:1060) ~[stardog-7.0.2.jar:?]
	... 10 more
ERROR 2019-11-04 13:59:55,308 [stardog-user-1] com.stardog.http.server.undertow.ErrorHandling:writeError(138): Unexpected error on the server
com.complexible.stardog.StardogException: java.lang.String cannot be cast to java.lang.Boolean
	at com.complexible.stardog.StardogKernel.getConnection(StardogKernel.java:1126) ~[stardog-7.0.2.jar:?]
	at com.complexible.stardog.protocols.http.server.KernelHttpService$ConnectionOptions.connect(KernelHttpService.java:117) ~[stardog-protocols-http-server-7.0.2.jar:?]
	at com.complexible.stardog.protocols.http.server.KernelHttpService.openConnection(KernelHttpService.java:68) ~[stardog-protocols-http-server-7.0.2.jar:?]
	at com.complexible.stardog.protocols.http.server.SPARQLProtocol.executeQuery(SPARQLProtocol.java:111) ~[stardog-protocols-http-server-7.0.2.jar:?]
	at com.complexible.stardog.protocols.http.server.SPARQLProtocol.post(SPARQLProtocol.java:92) ~[stardog-protocols-http-server-7.0.2.jar:?]
	at com.stardog.http.server.undertow.jaxrs.ExtractRoutes.lambda$handleIt$5(ExtractRoutes.java:192) ~[stardog-protocols-http-server-7.0.2.jar:?]
	at org.apache.shiro.subject.support.SubjectRunnable.doRun(SubjectRunnable.java:120) [shiro-core-1.3.0.jar:1.3.0]
	at org.apache.shiro.subject.support.SubjectRunnable.run(SubjectRunnable.java:108) [shiro-core-1.3.0.jar:1.3.0]
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:1.8.0_222]
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:1.8.0_222]
	at java.lang.Thread.run(Thread.java:748) [?:1.8.0_222]
Caused by: java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Boolean
	at com.complexible.stardog.StardogKernel.getConnection(StardogKernel.java:1060) ~[stardog-7.0.2.jar:?]
	... 10 more

```

I have executed `stardog-admin db offline stardog && stardog-admin db repair stardog`, which took about 2h and yielded no results (still the same exception).

I have executed `stardog-admin db optimize stardog` as well to see if this helps, but the query still fails with the same exception.

In addition to that restore process on stardog 7 was painfully slow:

```auto
# 8 cores, ssd drive
# STARDOG_SERVER_JAVA_ARGS=-Xms8g -Xmx8g -XX:MaxDirectMemorySize=16g
Node XXXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXX: Successfully restored database 'stardog' from Backup(/backups/20XX-XX-XX) in 02:27:57.736.

```

The size of the directories after the backup restoration:

```auto
bash-5.0# du -d 1 -h
4.0K	./tmp_sst_data
16.0K	./system
4.0K	./.spilling
5.3G	./data
466.5M	./stardog
29.2G	.

```

What can be attempted to fix the database?

---

<div class="post-metadata">

### Author: ![stephen](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.stardog.com/stephen/32/27_2.png) [@stephen](https://community.stardog.com/u/stephen)
#### Post date: [November 4, 2019, 3:08pm UTC](https://community.stardog.com/t/com-complexible-stardog-stardogexception-java-lang-string-cannot-be-cast-to-java-lang-boolean/2070/2 "2019-11-04T15:08:38Z")

</div>

Hi,

We've seen an error like this before with a migration. Try the following:

```auto
export AUTH=`echo -n admin:admin | base64` # Replace with your actual user:password, obviously don't include in output
clear # Just to be sure
# Again, replace port and myDb with the correct values
curl --url http://localhost:<port>/admin/databases/<myDb>/options \
  --header "Authorization: Basic $AUTH"

```

Take a look in the output and see if there's a boolean option that happens to have a string value. In previous cases it was specifically `"security.named.graphs": "true",`

Once you find the rogue values, you would just need to toggle the option back and forth in the command line to massage it back to a proper boolean value:

```auto
stardog-admin metadata set myDb -o security.named.graphs=false
stardog-admin metadata set myDb -o security.named.graphs=true

```

---

<div class="post-metadata">

### Author: ![earthquakesan](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.stardog.com/earthquakesan/32/421_2.png) [@earthquakesan](https://community.stardog.com/u/earthquakesan)
#### Post date: [November 5, 2019, 12:04pm UTC](https://community.stardog.com/t/com-complexible-stardog-stardogexception-java-lang-string-cannot-be-cast-to-java-lang-boolean/2070/3 "2019-11-05T12:04:52Z")

</div>

Hi Stephen,

that was exactly the problem. Resetting the value fixed it. Thanks for the hint.

Is it a known bug? Does it happen always during 6 --\> 7 db migration?

---

<div class="post-metadata">

### Author: ![stephen](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.stardog.com/stephen/32/27_2.png) [@stephen](https://community.stardog.com/u/stephen)
#### Post date: [November 5, 2019, 12:39pm UTC](https://community.stardog.com/t/com-complexible-stardog-stardogexception-java-lang-string-cannot-be-cast-to-java-lang-boolean/2070/4 "2019-11-05T12:39:27Z")

</div>

This is exactly the second time we've heard of it happening, so we're not entirely sure of the cause. Most migrations from 6 -\> 7 go just fine.

---

<div class="post-metadata">

### Author: ![earthquakesan](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.stardog.com/earthquakesan/32/421_2.png) [@earthquakesan](https://community.stardog.com/u/earthquakesan)
#### Post date: [November 5, 2019, 12:52pm UTC](https://community.stardog.com/t/com-complexible-stardog-stardogexception-java-lang-string-cannot-be-cast-to-java-lang-boolean/2070/5 "2019-11-05T12:52:00Z")

</div>

Okay, if it is not really reproducible, I think, we should not spend time on this. Thanks for the support!

---

<div class="post-metadata">

### Author: ![joergunbehauen](https://avatars.discourse-cdn.com/v4/letter/j/7c8e57/32.png) [@joergunbehauen](https://community.stardog.com/u/joergunbehauen)
#### Post date: [November 5, 2019, 4:01pm UTC](https://community.stardog.com/t/com-complexible-stardog-stardogexception-java-lang-string-cannot-be-cast-to-java-lang-boolean/2070/6 "2019-11-05T16:01:40Z")

</div>

I was able reproduce it:

This happens in Stardog Studio Version 1.13.1 (1.13.1.13021)  
Execute a query on a stardog 6.2.3  
Then switch to stardog 7.0.2, execute a query  
The switch back to stardog 6.2.3 and execute the query -\> and there is the error message

Restarting Stardog studio solves the problem.

---

<div class="post-metadata">

### Author: ![joergunbehauen](https://avatars.discourse-cdn.com/v4/letter/j/7c8e57/32.png) [@joergunbehauen](https://community.stardog.com/u/joergunbehauen)
#### Post date: [November 5, 2019, 4:25pm UTC](https://community.stardog.com/t/com-complexible-stardog-stardogexception-java-lang-string-cannot-be-cast-to-java-lang-boolean/2070/7 "2019-11-05T16:25:22Z")

</div>

Ok, now i got this issue on my stardog 6.2.3 databases on my test instance. Not sure if the studio is causing this, but it might.