diff --git a/src/main/kotlin/org/jetbrains/research/testspark/display/ErrorMessageNormalizer.kt b/src/main/kotlin/org/jetbrains/research/testspark/display/ErrorMessageNormalizer.kt
new file mode 100644
index 000000000..360162105
--- /dev/null
+++ b/src/main/kotlin/org/jetbrains/research/testspark/display/ErrorMessageNormalizer.kt
@@ -0,0 +1,46 @@
+package org.jetbrains.research.testspark.display
+
+/**
+ * The ErrorMessageNormalizer class is responsible for normalizing error messages by inserting "<br/>" tags after every block size characters.
+ */
+object ErrorMessageNormalizer {
+    const val BLOCK_SIZE = 100
+
+    const val SEPARATOR = "<br/>"
+
+    /**
+     * Normalizes an error message by inserting "<br/>" tags after every block size characters,
+     * except if there is already a "<br/>" tag within the blockSize characters.
+     * If the string length is a multiple of blockSize and the last character is a "<br/>" tag,
+     * it is removed from the result.
+     *
+     * @param error The error message to be normalized.
+     * @return The normalized error message.
+     */
+    fun normalize(error: String): String {
+        // init variables
+        val builder = StringBuilder()
+        var lastIndex = 0
+
+        // string separating
+        while (lastIndex < error.length) {
+            val nextIndex = (lastIndex + BLOCK_SIZE).coerceAtMost(error.length)
+            val substring = error.substring(lastIndex, nextIndex)
+
+            if (!substring.contains(SEPARATOR)) {
+                builder.append(substring).append(SEPARATOR)
+            } else {
+                builder.append(substring)
+            }
+
+            lastIndex = nextIndex
+        }
+
+        // remove the last <br/> if the string length is a multiple of the block size, and it didn't have <br/>
+        if (builder.endsWith(SEPARATOR) && (error.length % BLOCK_SIZE == 0)) {
+            builder.deleteRange(builder.length - SEPARATOR.length, builder.length)
+        }
+
+        return builder.toString()
+    }
+}
diff --git a/src/main/kotlin/org/jetbrains/research/testspark/display/TestCasePanelFactory.kt b/src/main/kotlin/org/jetbrains/research/testspark/display/TestCasePanelFactory.kt
index 99b0ec5ab..dd5ba905d 100644
--- a/src/main/kotlin/org/jetbrains/research/testspark/display/TestCasePanelFactory.kt
+++ b/src/main/kotlin/org/jetbrains/research/testspark/display/TestCasePanelFactory.kt
@@ -326,7 +326,7 @@ class TestCasePanelFactory(
             errorLabel.isVisible = false
         } else {
             errorLabel.isVisible = true
-            errorLabel.toolTipText = error
+            errorLabel.toolTipText = ErrorMessageNormalizer.normalize(error)
         }
     }
 
diff --git a/src/test/kotlin/org/jetbrains/research/testspark/helper/ErrorMessageNormalizerTest.kt b/src/test/kotlin/org/jetbrains/research/testspark/helper/ErrorMessageNormalizerTest.kt
new file mode 100644
index 000000000..a608c1413
--- /dev/null
+++ b/src/test/kotlin/org/jetbrains/research/testspark/helper/ErrorMessageNormalizerTest.kt
@@ -0,0 +1,68 @@
+package org.jetbrains.research.testspark.display
+
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
+
+class ErrorMessageNormalizerTest {
+
+    /**
+     * Test with a string length less than BLOCK_SIZE and no separators.
+     */
+    @Test
+    fun testNormalizeWithNoSeparator() {
+        val input = "a".repeat(ErrorMessageNormalizer.BLOCK_SIZE - 1)
+        val expected = "a".repeat(ErrorMessageNormalizer.BLOCK_SIZE - 1) + ErrorMessageNormalizer.SEPARATOR
+        val result = ErrorMessageNormalizer.normalize(input)
+        assertEquals(expected, result)
+    }
+
+    /**
+     * Test with a string length exactly equal to BLOCK_SIZE and no separators.
+     */
+    @Test
+    fun testNormalizeWithExactBlockSizeNoSeparator() {
+        val input = "a".repeat(ErrorMessageNormalizer.BLOCK_SIZE)
+        val expected = "a".repeat(ErrorMessageNormalizer.BLOCK_SIZE)
+        val result = ErrorMessageNormalizer.normalize(input)
+        assertEquals(expected, result)
+    }
+
+    /**
+     * Test with a string length greater than BLOCK_SIZE and no separators.
+     */
+    @Test
+    fun testNormalizeWithMultipleBlocksNoSeparator() {
+        val input = "a".repeat(ErrorMessageNormalizer.BLOCK_SIZE * 2 + 50)
+        val expected = "a".repeat(ErrorMessageNormalizer.BLOCK_SIZE) + ErrorMessageNormalizer.SEPARATOR +
+            "a".repeat(ErrorMessageNormalizer.BLOCK_SIZE) + ErrorMessageNormalizer.SEPARATOR +
+            "a".repeat(50) + ErrorMessageNormalizer.SEPARATOR
+        val result = ErrorMessageNormalizer.normalize(input)
+        assertEquals(expected, result)
+    }
+
+    /**
+     * Test with an empty string.
+     */
+    @Test
+    fun testNormalizeEmptyString() {
+        val input = ""
+        val expected = ""
+        val result = ErrorMessageNormalizer.normalize(input)
+        assertEquals(expected, result)
+    }
+
+    /**
+     * Test with a string containing multiple separators.
+     */
+    @Test
+    fun testNormalizeWithMultipleSeparators() {
+        val input = "a".repeat(40) + ErrorMessageNormalizer.SEPARATOR +
+            "b".repeat(40) + ErrorMessageNormalizer.SEPARATOR +
+            "c".repeat(20)
+        val expected = "a".repeat(40) + ErrorMessageNormalizer.SEPARATOR +
+            "b".repeat(40) + ErrorMessageNormalizer.SEPARATOR +
+            "c".repeat(20) + ErrorMessageNormalizer.SEPARATOR
+        val result = ErrorMessageNormalizer.normalize(input)
+        assertEquals(expected, result)
+    }
+}