diff --git a/components/dashboard/src/start/StartPage.tsx b/components/dashboard/src/start/StartPage.tsx
index 6c0bb476b1a346..3f5bde5fa02b9d 100644
--- a/components/dashboard/src/start/StartPage.tsx
+++ b/components/dashboard/src/start/StartPage.tsx
@@ -96,5 +96,5 @@ function StartError(props: { error: StartWorkspaceError }) {
   if (!error) {
     return null;
   }
-  return <p className="text-base text-gitpod-red">{error.message}</p>;
+  return <p className="text-base text-gitpod-red w-96">{error.message}</p>;
 }
diff --git a/components/server/src/github/github-context-parser.ts b/components/server/src/github/github-context-parser.ts
index d147ef82a550c2..daebef9bccc1a7 100644
--- a/components/server/src/github/github-context-parser.ts
+++ b/components/server/src/github/github-context-parser.ts
@@ -299,9 +299,12 @@ export class GithubContextParser extends AbstractContextParser implements IConte
                 if (tryIssueContext) {
                     return this.handleIssueContext({span}, user, host, owner, repoName, pullRequestNr, false);
                 } else {
-                    throw new Error(`Couldn't find issue or pull request #${pullRequestNr} in repository ${owner}/${repoName}.`)
+                    throw new Error(`Could not find issue or pull request #${pullRequestNr} in repository ${owner}/${repoName}.`)
                 }
             }
+            if (pr.headRef === null) {
+                throw new Error(`Could not open pull request ${owner}/${repoName}#${pullRequestNr}. Source branch may have been removed.`);
+            }
             return <PullRequestContext>{
                 title: pr.title,
                 repository: this.toRepository(host, pr.headRef.repository),