diff --git a/models/issue.go b/models/issue.go
index 804d7dc101..9e63ac4e58 100644
--- a/models/issue.go
+++ b/models/issue.go
@@ -36,7 +36,7 @@ type Issue struct {
 	OriginalAuthor   string
 	OriginalAuthorID int64      `xorm:"index"`
 	Title            string     `xorm:"name"`
-	Content          string     `xorm:"TEXT"`
+	Content          string     `xorm:"LONGTEXT"`
 	RenderedContent  string     `xorm:"-"`
 	Labels           []*Label   `xorm:"-"`
 	MilestoneID      int64      `xorm:"INDEX"`
diff --git a/models/issue_comment.go b/models/issue_comment.go
index 06b74dff85..10a7d0b114 100644
--- a/models/issue_comment.go
+++ b/models/issue_comment.go
@@ -155,12 +155,12 @@ type Comment struct {
 	CommitID        int64
 	Line            int64 // - previous line / + proposed line
 	TreePath        string
-	Content         string `xorm:"TEXT"`
+	Content         string `xorm:"LONGTEXT"`
 	RenderedContent string `xorm:"-"`
 
 	// Path represents the 4 lines of code cemented by this comment
 	Patch       string `xorm:"-"`
-	PatchQuoted string `xorm:"TEXT patch"`
+	PatchQuoted string `xorm:"LONGTEXT patch"`
 
 	CreatedUnix timeutil.TimeStamp `xorm:"INDEX created"`
 	UpdatedUnix timeutil.TimeStamp `xorm:"INDEX updated"`
diff --git a/models/migrations/migrations.go b/models/migrations/migrations.go
index 13ed70bc4f..6c35d34c97 100644
--- a/models/migrations/migrations.go
+++ b/models/migrations/migrations.go
@@ -334,6 +334,8 @@ var migrations = []Migration{
 	NewMigration("Unwrap ldap.Sources", unwrapLDAPSourceCfg),
 	// v190 -> v191
 	NewMigration("Add agit flow pull request support", addAgitFlowPullRequest),
+	// v191 -> v192
+	NewMigration("Alter issue/comment table TEXT fields to LONGTEXT", alterIssueAndCommentTextFieldsToLongText),
 }
 
 // GetCurrentDBVersion returns the current db version
diff --git a/models/migrations/v191.go b/models/migrations/v191.go
new file mode 100644
index 0000000000..10dfad4f04
--- /dev/null
+++ b/models/migrations/v191.go
@@ -0,0 +1,29 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package migrations
+
+import (
+	"code.gitea.io/gitea/modules/setting"
+	"xorm.io/xorm"
+)
+
+func alterIssueAndCommentTextFieldsToLongText(x *xorm.Engine) error {
+
+	sess := x.NewSession()
+	defer sess.Close()
+	if err := sess.Begin(); err != nil {
+		return err
+	}
+
+	if setting.Database.UseMySQL {
+		if _, err := sess.Exec("ALTER TABLE `issue` CHANGE `content` `content` LONGTEXT"); err != nil {
+			return err
+		}
+		if _, err := sess.Exec("ALTER TABLE `comment` CHANGE `content` `content` LONGTEXT, CHANGE `patch` `patch` LONGTEXT"); err != nil {
+			return err
+		}
+	}
+	return sess.Commit()
+}