diff --git a/src/main/kotlin/com/sourcegraph/cody/inspections/CodyFixHighlightPass.kt b/src/main/kotlin/com/sourcegraph/cody/inspections/CodyFixHighlightPass.kt
index 107d23d072..b521f1e844 100644
--- a/src/main/kotlin/com/sourcegraph/cody/inspections/CodyFixHighlightPass.kt
+++ b/src/main/kotlin/com/sourcegraph/cody/inspections/CodyFixHighlightPass.kt
@@ -1,30 +1,66 @@
 package com.sourcegraph.cody.inspections
 
-import com.intellij.codeHighlighting.*
+import com.intellij.codeHighlighting.Pass
+import com.intellij.codeHighlighting.TextEditorHighlightingPass
+import com.intellij.codeHighlighting.TextEditorHighlightingPassFactory
+import com.intellij.codeHighlighting.TextEditorHighlightingPassFactoryRegistrar
+import com.intellij.codeHighlighting.TextEditorHighlightingPassRegistrar
 import com.intellij.codeInsight.daemon.DaemonCodeAnalyzer
-import com.intellij.codeInsight.daemon.impl.*
+import com.intellij.codeInsight.daemon.impl.DaemonCodeAnalyzerImpl
+import com.intellij.codeInsight.daemon.impl.HighlightInfo
 import com.intellij.lang.annotation.HighlightSeverity
+import com.intellij.openapi.application.ApplicationManager
 import com.intellij.openapi.diagnostic.Logger
 import com.intellij.openapi.editor.Editor
 import com.intellij.openapi.progress.ProgressIndicator
 import com.intellij.openapi.progress.util.ProgressIndicatorUtils
 import com.intellij.openapi.project.Project
 import com.intellij.psi.PsiFile
+import com.intellij.util.concurrency.AppExecutorUtil
 import com.sourcegraph.cody.agent.CodyAgentService
 import com.sourcegraph.cody.agent.intellij_extensions.codyRange
 import com.sourcegraph.cody.agent.protocol.ProtocolTextDocument
-import com.sourcegraph.cody.agent.protocol_generated.*
+import com.sourcegraph.cody.agent.protocol_generated.CodeActions_ProvideParams
+import com.sourcegraph.cody.agent.protocol_generated.Diagnostics_PublishParams
+import com.sourcegraph.cody.agent.protocol_generated.ProtocolDiagnostic
+import com.sourcegraph.cody.agent.protocol_generated.ProtocolLocation
+import com.sourcegraph.cody.agent.protocol_generated.Range
 import java.util.concurrent.CompletableFuture
+import java.util.concurrent.TimeUnit
+import java.util.concurrent.TimeoutException
+import java.util.concurrent.atomic.AtomicReference
 
 class CodyFixHighlightPass(val file: PsiFile, val editor: Editor) :
     TextEditorHighlightingPass(file.project, editor.document, false) {
 
   private val logger = Logger.getInstance(CodyFixHighlightPass::class.java)
-  private val protocolTextDocument = ProtocolTextDocument.fromVirtualFile(file.virtualFile)
   private var myHighlights = emptyList<HighlightInfo>()
   private val myRangeActions = mutableMapOf<Range, List<CodeActionQuickFixParams>>()
 
+  // We are invoked by the superclass on a daemon/worker thread, but we need the EDT
+  // for this and perhaps other things (e.g. Document.codyRange). So we set things up
+  // to block the caller and fetch what we need on the EDT.
+  private val protocolTextDocumentFuture: CompletableFuture<ProtocolTextDocument> =
+      CompletableFuture.supplyAsync(
+          {
+            val result = AtomicReference<ProtocolTextDocument>()
+            ApplicationManager.getApplication().invokeAndWait {
+              result.set(ProtocolTextDocument.fromVirtualFile(file.virtualFile))
+            }
+            result.get()
+          },
+          AppExecutorUtil.getAppExecutorService())
+
   override fun doCollectInformation(progress: ProgressIndicator) {
+    // Fetch the protocol text document on the EDT.
+    val protocolTextDocument =
+        try {
+          protocolTextDocumentFuture.get(5, TimeUnit.SECONDS)
+        } catch (e: TimeoutException) {
+          logger.warn("Timeout fetching protocol text document")
+          return
+        }
+
     if (!DaemonCodeAnalyzer.getInstance(file.project).isHighlightingAvailable(file) ||
         progress.isCanceled) {
       // wait until after code-analysis is completed
@@ -41,17 +77,25 @@ class CodyFixHighlightPass(val file: PsiFile, val editor: Editor) :
             // TODO: We need to check how Enum comparison works to check if we can do things like >=
             // HighlightSeverity.INFO
             .filter { it.severity == HighlightSeverity.ERROR }
-            .map {
-              ProtocolDiagnostic(
-                  message = it.description,
-                  severity =
-                      "error", // TODO: Wait for CODY-2882. This isn't currently used by the agent,
-                  // so we just keep our lives simple.
-                  location =
-                      ProtocolLocation(
-                          uri = protocolTextDocument.uri,
-                          range = document.codyRange(it.startOffset, it.endOffset)),
-                  code = it.problemGroup?.problemName)
+            .mapNotNull {
+              try {
+                ProtocolDiagnostic(
+                    message = it.description,
+                    severity =
+                        "error", // TODO: Wait for CODY-2882. This isn't currently used by the
+                    // agent,
+                    // so we just keep our lives simple.
+                    location =
+                        // TODO: Rik Nauta -- Got incorrect range; see QA report Aug 6 2024.
+                        ProtocolLocation(
+                            uri = protocolTextDocument.uri,
+                            range = document.codyRange(it.startOffset, it.endOffset)),
+                    code = it.problemGroup?.problemName)
+              } catch (x: Exception) {
+                // Don't allow range errors to throw user-visible exceptions (QA found this).
+                logger.warn("Failed to convert highlight to protocol diagnostic", x)
+                null
+              }
             }
     val done = CompletableFuture<Unit>()
     CodyAgentService.withAgentRestartIfNeeded(file.project) { agent ->