diff --git a/scm-core/src/main/java/sonia/scm/repository/work/WorkdirProvider.java b/scm-core/src/main/java/sonia/scm/repository/work/WorkdirProvider.java
index c8ac315d03..ce73303aee 100644
--- a/scm-core/src/main/java/sonia/scm/repository/work/WorkdirProvider.java
+++ b/scm-core/src/main/java/sonia/scm/repository/work/WorkdirProvider.java
@@ -55,15 +55,16 @@ public class WorkdirProvider implements ServletContextListener {
     @ConfigValue(key = "workDir", defaultValue = "", description = "Working directory for internal repository operations") String workDir,
     RepositoryLocationResolver repositoryLocationResolver
     ) {
-    this(new File(!Strings.isNullOrEmpty(workDir) ? workDir : System.getProperty("java.io.tmpdir") , "scm-work"), repositoryLocationResolver, workDir == null);
+    this(new File(Strings.isNullOrEmpty(workDir) ? System.getProperty("java.io.tmpdir") : workDir, "scm-work"), repositoryLocationResolver, workDir == null);
   }
 
   public WorkdirProvider(File rootDirectory, RepositoryLocationResolver repositoryLocationResolver, boolean useRepositorySpecificDir) {
-    this.rootDirectory = rootDirectory;
+    this.rootDirectory = rootDirectory.isAbsolute() ? rootDirectory : new File(System.getProperty("basedir", "."), rootDirectory.getPath());
+    LOG.info("using {} as work directory", this.rootDirectory);
     this.repositoryLocationResolver = repositoryLocationResolver;
     this.useRepositorySpecificDir = useRepositorySpecificDir;
     if (!rootDirectory.exists() && !rootDirectory.mkdirs()) {
-      throw new IllegalStateException("could not create pool directory " + rootDirectory);
+      throw new IllegalStateException("could not create pool directory " + this.rootDirectory);
     }
   }
 
diff --git a/scm-webapp/src/main/java/sonia/scm/plugin/ConfigurationResolver.java b/scm-webapp/src/main/java/sonia/scm/plugin/ConfigurationResolver.java
index 8fab7514e8..e790806b7a 100644
--- a/scm-webapp/src/main/java/sonia/scm/plugin/ConfigurationResolver.java
+++ b/scm-webapp/src/main/java/sonia/scm/plugin/ConfigurationResolver.java
@@ -58,7 +58,7 @@ public class ConfigurationResolver {
       rootNode = new ObjectMapper(new YAMLFactory()).readTree(resource).get("webapp");
       WebappConfigProvider.setConfigBindings(readConfigurationFile(rootNode));
     } catch (IOException e) {
-      throw new RuntimeException(e);
+      throw new IllegalArgumentException("failed to read configuration from file " + configPath, e);
     }
   }
 
@@ -100,7 +100,9 @@ public class ConfigurationResolver {
         return Optional.empty();
       }
     }
-
+    if (node.isNull()) {
+      return Optional.empty();
+    }
     return Optional.of(node.asText());
   }
 
@@ -112,6 +114,6 @@ public class ConfigurationResolver {
   }
 
   private String createEnvKey(String key) {
-    return PREFIX + key.toUpperCase(Locale.ENGLISH).replaceAll("\\.-/", "_");
+    return PREFIX + key.toUpperCase(Locale.ENGLISH).replaceAll("[.\\-/]", "_");
   }
 }
diff --git a/scm-webapp/src/test/java/sonia/scm/plugin/ConfigurationResolverTest.java b/scm-webapp/src/test/java/sonia/scm/plugin/ConfigurationResolverTest.java
index e59c8b20d4..d86b2f5a2c 100644
--- a/scm-webapp/src/test/java/sonia/scm/plugin/ConfigurationResolverTest.java
+++ b/scm-webapp/src/test/java/sonia/scm/plugin/ConfigurationResolverTest.java
@@ -24,11 +24,11 @@
 
 package sonia.scm.plugin;
 
-import com.google.common.collect.ImmutableMap;
 import org.junit.jupiter.api.Test;
 import sonia.scm.config.WebappConfigProvider;
 
 import java.util.Collections;
+import java.util.Map;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
@@ -54,11 +54,13 @@ class ConfigurationResolverTest {
 
   @Test
   void shouldResolveConfiguration_WithEnv() {
-    ConfigurationResolver configurationResolver = new ConfigurationResolver(ImmutableMap.of("SCM_WEBAPP_CONTEXTPATH", "/scm"), "sonia/scm/plugin/config.yml");
+    ConfigurationResolver configurationResolver = new ConfigurationResolver(Map.of("SCM_WEBAPP_CONTEXTPATH", "/scm", "SCM_WEBAPP_HTTPS_SSL", "true"), "sonia/scm/plugin/config.yml");
 
     String port = configurationResolver.resolve("contextPath", "/");
+    String ssl = configurationResolver.resolve("https.ssl", "false");
 
     assertThat(port).isEqualTo("/scm");
+    assertThat(ssl).isEqualTo("true");
   }
 
   @Test
@@ -80,9 +82,12 @@ class ConfigurationResolverTest {
 
   @Test
   void shouldReadNullValuesFromConfigYaml() {
-    new ConfigurationResolver(Collections.emptyMap(), "sonia/scm/plugin/configWithNull.yml");
+    ConfigurationResolver configurationResolver = new ConfigurationResolver(Collections.emptyMap(), "sonia/scm/plugin/configWithNull.yml");
 
-    assertThat(WebappConfigProvider.resolveAsBoolean("redirect")).contains(true);
     assertThat(WebappConfigProvider.resolveAsInteger("https.keyType")).isEmpty();
+    assertThat(WebappConfigProvider.resolveAsString("https.keyType")).isEmpty();
+    assertThat(WebappConfigProvider.resolveAsBoolean("https.keyType")).isEmpty();
+
+    assertThat(configurationResolver.resolve("https.keyType", "other")).isEqualTo("other");
   }
 }