I retrieved the following error today when trying to attach files to a page in my personal space:

Cause

org.apache.velocity.exception.MethodInvocationException: Invocation of method 'hasAttachFilePermissions' in class com.atlassian.confluence.pages.actions.InsertImageInDraftAction threw exception java.lang.IllegalStateException: Space does not exist at /users/insertimage-popup-common.vm[line 25, column 52]
at org.apache.velocity.runtime.parser.node.ASTMethod.handleInvocationException(ASTMethod.java:337)

caused by: java.lang.IllegalStateException: Space does not exist
at com.atlassian.confluence.security.delegate.AttachmentPermissionsDelegate.canCreate(AttachmentPermissionsDelegate.java:88)
Stack Trace:[hide]

org.apache.velocity.exception.MethodInvocationException: Invocation of method 'hasAttachFilePermissions' in class com.atlassian.confluence.pages.actions.InsertImageInDraftAction threw exception java.lang.IllegalStateException: Space does not exist at /users/insertimage-popup-common.vm[line 25, column 52]
at org.apache.velocity.runtime.parser.node.ASTMethod.handleInvocationException(ASTMethod.java:337)
at org.apache.velocity.runtime.parser.node.ASTMethod.execute(ASTMethod.java:284)
at org.apache.velocity.runtime.parser.node.ASTReference.execute(ASTReference.java:252)
at org.apache.velocity.runtime.parser.node.ASTReference.evaluate(ASTReference.java:460)
at org.apache.velocity.runtime.parser.node.ASTAndNode.evaluate(ASTAndNode.java:106)
at org.apache.velocity.runtime.parser.node.ASTAndNode.value(ASTAndNode.java:74)
at org.apache.velocity.runtime.parser.node.ASTExpression.value(ASTExpression.java:71)
at org.apache.velocity.runtime.parser.node.ASTSetDirective.render(ASTSetDirective.java:142)
at org.apache.velocity.runtime.parser.node.ASTBlock.render(ASTBlock.java:72)
at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:336)
at org.apache.velocity.runtime.parser.node.ASTIfStatement.render(ASTIfStatement.java:106)
at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:336)
at org.apache.velocity.runtime.directive.Parse.render(Parse.java:260)
at org.apache.velocity.runtime.parser.node.ASTDirective.render(ASTDirective.java:175)
at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:336)
at org.apache.velocity.Template.merge(Template.java:328)
at org.apache.velocity.Template.merge(Template.java:235)