Quest minimum level

Overview
Update 18 silently added hard lower limits for character level to be able to enter a quest of a given level.

For Heroic quests (quests with base quest level 1 to 20) the minimum character level that can enter is determined by the quest's base level (difficulty selected does not matter), as shown on the table below. For example, The Pit has a base quest level of 7, so the minimum character level that can enter the quest is 4; by the table, characters of level 4 or higher can enter this quest on any difficulty setting.

For Epic quests (quests with base quest level of 21+) the minimum character level is 20. This excludes raids with a minimum level of 30 or higher - characters must be at most four levels under the raid's level to enter it.
 * Before Update 23, there was a restriction in place for all quests. (a maximum of four level difference between character level and difficulty-modified quest level).
 * Some chain bestowers (for example the Wheloon / Storm Horns chains) still refuse to talk to low-level characters and presumably follow the old level requirements.
 * Certain older epic quests, such as the level 28 quest Brothers of the Forge, still have this restriction, possibly erroneously.

The same restrictions apply to Wilderness Adventure Areas. It does not apply to Challenges which instead have specific minimum levels for each challenge (the lowest selectable level for the challenge is also the minimum level which characters can enter it, and characters of that level or higher can enter at any selectable level).

Problem Quests

 * In the Delera's Tomb chain, the four main quests progress steadily in level from Level 5 to Level 8, with a short non-combat Level 6 quest, Return to Delera's Tomb, before the Level 8 finale. Hargo Kimmare, the NPC who advances the chain to this non-combat quest, will not advance the chain to anyone who does not qualify for the level 8 final quest; i.e. he will not give this Level 6 quest to anyone who is not Level 5 or higher.
 * The Twilight Forge (base level 11) raid can be started by characters of level 8 but you must be level 9 to continue into The Titan Awakes (base level 12) when you get to the end.
 * Ruins of Gianthold (level 13) wilderness area should allow characters of level 9 but you must be level 10 to enter the wilderness to access them, so the level 13 quests in the area cannot be entered until level 10 (even though the quests can be acquired at level 9).

Entire Party Rule
For Heroic quests, all members of the party must meet or exceed the quest minimum level for anyone in the party to be able to enter (or re-enter) the quest. For Epic quests, all members of the party must be at least level 20 for anyone in the party to be able to enter the quest.

If the minimum level requirement is not met, upon attempting to enter a quest, one or more party members will receive the message "(Error): Each member of your party must meet the requirements for this quest", and be prevented from entering the quest until the minimum level requirements are met.

For example: if someone enters the quest and then summons a lower-level hireling (below the quest minimum level), no one else in the party will be able to enter the quest until that hireling is dismissed. After all the party members that need to enter the quest are inside, you may summon the hireling again (or invite other low-level players to the party to chat etc. even-though they cannot enter the quest).

Bug
There's a bug where some party member(s) can be blocked entry to a quest, given the same error message as above. The members who cannot enter must log out and then back in, or the group needs to disband (completely!) and reform to continue. This has been reported to occur when...
 * a character takes a level while questing in a party (and their previous level was below the minimum requirements of a new quest).
 * a character hits Level 20 and later begins Epic quests (without logging out/back in)
 * an Iconic character is created and begins questing (without logging out/back in) (DDO Forums, DDO Forums)

Note that the character receiving the message may not be the one causing it, and that character may have entered the quest without a problem. (DDO Forums)

It seems that the game remembers the levels of party members when they log in or join the group, and then uses that number to check for level requirements. For example: However, it has also been (rarely) reported to occur spontaneously, unrelated to leveling.
 * A group containing a level 1 character starts doing Harbor quests (base level 2 quests, minimum character level 1). The level 1 quickly takes their second level. However, when the group tries to do part 3 of Waterworks chain (base level 4 quest, minimum character level 2), some party members cannot enter.
 * A group of level 18 characters quest together, then they take level 20 and want to step into epic Devil Assault. They open the group for new members. Some party members cannot enter, even though all characters are level 20 or higher.
 * A group is formed while a character is taking their level after an epic reincarnation. After taking level 20, some party members can be prevented from entering epic content.

See also:
 * Quests by level
 * Adventure Packs (table sortable by level)
 * Free to Play Quests (table sortable by level)
 * Specific Quests by name